kernel - Provide descriptions for lwkt.* and debug.* sysctl's
[dragonfly.git] / sys / kern / lwkt_thread.c
CommitLineData
8ad65e08 1/*
3b998fa9 2 * Copyright (c) 2003-2010 The DragonFly Project. All rights reserved.
60f60350 3 *
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4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
60f60350 6 *
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7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
60f60350 10 *
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11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
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14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
16 * distribution.
17 * 3. Neither the name of The DragonFly Project nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
60f60350 20 *
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21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
8ad65e08 32 * SUCH DAMAGE.
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33 */
34
35/*
36 * Each cpu in a system has its own self-contained light weight kernel
37 * thread scheduler, which means that generally speaking we only need
38 * to use a critical section to avoid problems. Foreign thread
39 * scheduling is queued via (async) IPIs.
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40 */
41
42#include <sys/param.h>
43#include <sys/systm.h>
44#include <sys/kernel.h>
45#include <sys/proc.h>
46#include <sys/rtprio.h>
b37f18d6 47#include <sys/kinfo.h>
8ad65e08 48#include <sys/queue.h>
7d0bac62 49#include <sys/sysctl.h>
99df837e 50#include <sys/kthread.h>
f1d1c3fa 51#include <machine/cpu.h>
99df837e 52#include <sys/lock.h>
f6bf3af1 53#include <sys/caps.h>
9d265729 54#include <sys/spinlock.h>
57aa743c 55#include <sys/ktr.h>
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56
57#include <sys/thread2.h>
58#include <sys/spinlock2.h>
684a93c4 59#include <sys/mplock2.h>
f1d1c3fa 60
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61#include <sys/dsched.h>
62
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63#include <vm/vm.h>
64#include <vm/vm_param.h>
65#include <vm/vm_kern.h>
66#include <vm/vm_object.h>
67#include <vm/vm_page.h>
68#include <vm/vm_map.h>
69#include <vm/vm_pager.h>
70#include <vm/vm_extern.h>
7d0bac62 71
99df837e 72#include <machine/stdarg.h>
96728c05 73#include <machine/smp.h>
99df837e 74
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75#if !defined(KTR_CTXSW)
76#define KTR_CTXSW KTR_ALL
77#endif
78KTR_INFO_MASTER(ctxsw);
a1f0fb66
AE
79KTR_INFO(KTR_CTXSW, ctxsw, sw, 0, "#cpu[%d].td = %p",
80 sizeof(int) + sizeof(struct thread *));
81KTR_INFO(KTR_CTXSW, ctxsw, pre, 1, "#cpu[%d].td = %p",
82 sizeof(int) + sizeof(struct thread *));
83KTR_INFO(KTR_CTXSW, ctxsw, newtd, 2, "#threads[%p].name = %s",
84 sizeof (struct thread *) + sizeof(char *));
85KTR_INFO(KTR_CTXSW, ctxsw, deadtd, 3, "#threads[%p].name = <dead>", sizeof (struct thread *));
1541028a 86
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87static MALLOC_DEFINE(M_THREAD, "thread", "lwkt threads");
88
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89#ifdef INVARIANTS
90static int panic_on_cscount = 0;
91#endif
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92static __int64_t switch_count = 0;
93static __int64_t preempt_hit = 0;
94static __int64_t preempt_miss = 0;
95static __int64_t preempt_weird = 0;
f64b567c 96static __int64_t token_contention_count __debugvar = 0;
fb0f29c4 97static int lwkt_use_spin_port;
40aaf5fc 98static struct objcache *thread_cache;
05220613 99
88ebb169 100#ifdef SMP
e381e77c 101static void lwkt_schedule_remote(void *arg, int arg2, struct intrframe *frame);
88ebb169 102#endif
f9235b6d 103static void lwkt_fairq_accumulate(globaldata_t gd, thread_t td);
e381e77c 104
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105extern void cpu_heavy_restore(void);
106extern void cpu_lwkt_restore(void);
107extern void cpu_kthread_restore(void);
108extern void cpu_idle_restore(void);
109
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110/*
111 * We can make all thread ports use the spin backend instead of the thread
112 * backend. This should only be set to debug the spin backend.
113 */
114TUNABLE_INT("lwkt.use_spin_port", &lwkt_use_spin_port);
115
0f7a3396 116#ifdef INVARIANTS
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117SYSCTL_INT(_lwkt, OID_AUTO, panic_on_cscount, CTLFLAG_RW, &panic_on_cscount, 0,
118 "Panic if attempting to switch lwkt's while mastering cpusync");
0f7a3396 119#endif
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120SYSCTL_QUAD(_lwkt, OID_AUTO, switch_count, CTLFLAG_RW, &switch_count, 0,
121 "Number of switched threads");
9733f757 122SYSCTL_QUAD(_lwkt, OID_AUTO, preempt_hit, CTLFLAG_RW, &preempt_hit, 0,
0c52fa62 123 "Successful preemption events");
9733f757 124SYSCTL_QUAD(_lwkt, OID_AUTO, preempt_miss, CTLFLAG_RW, &preempt_miss, 0,
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125 "Failed preemption events");
126SYSCTL_QUAD(_lwkt, OID_AUTO, preempt_weird, CTLFLAG_RW, &preempt_weird, 0,
127 "Number of preempted threads.");
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128#ifdef INVARIANTS
129SYSCTL_QUAD(_lwkt, OID_AUTO, token_contention_count, CTLFLAG_RW,
130 &token_contention_count, 0, "spinning due to token contention");
38717797 131#endif
f9235b6d 132static int fairq_enable = 1;
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133SYSCTL_INT(_lwkt, OID_AUTO, fairq_enable, CTLFLAG_RW, &fairq_enable, 0,
134 "Turn on fairq priority accumulators");
77912481 135static int user_pri_sched = 0;
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136SYSCTL_INT(_lwkt, OID_AUTO, user_pri_sched, CTLFLAG_RW, &user_pri_sched, 0,
137 "");
fbc024e4 138static int preempt_enable = 1;
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139SYSCTL_INT(_lwkt, OID_AUTO, preempt_enable, CTLFLAG_RW, &preempt_enable, 0,
140 "Enable preemption");
fbc024e4 141
05220613 142
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143/*
144 * These helper procedures handle the runq, they can only be called from
145 * within a critical section.
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146 *
147 * WARNING! Prior to SMP being brought up it is possible to enqueue and
148 * dequeue threads belonging to other cpus, so be sure to use td->td_gd
149 * instead of 'mycpu' when referencing the globaldata structure. Once
150 * SMP live enqueuing and dequeueing only occurs on the current cpu.
4b5f931b 151 */
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152static __inline
153void
154_lwkt_dequeue(thread_t td)
155{
156 if (td->td_flags & TDF_RUNQ) {
75cdbe6c 157 struct globaldata *gd = td->td_gd;
4b5f931b 158
f1d1c3fa 159 td->td_flags &= ~TDF_RUNQ;
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160 TAILQ_REMOVE(&gd->gd_tdrunq, td, td_threadq);
161 gd->gd_fairq_total_pri -= td->td_pri;
162 if (TAILQ_FIRST(&gd->gd_tdrunq) == NULL)
163 atomic_clear_int_nonlocked(&gd->gd_reqflags, RQF_RUNNING);
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164 }
165}
166
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167/*
168 * Priority enqueue.
169 *
170 * NOTE: There are a limited number of lwkt threads runnable since user
171 * processes only schedule one at a time per cpu.
172 */
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173static __inline
174void
175_lwkt_enqueue(thread_t td)
176{
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177 thread_t xtd;
178
7f5d7ed7 179 if ((td->td_flags & (TDF_RUNQ|TDF_MIGRATING|TDF_BLOCKQ)) == 0) {
75cdbe6c 180 struct globaldata *gd = td->td_gd;
4b5f931b 181
f1d1c3fa 182 td->td_flags |= TDF_RUNQ;
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183 xtd = TAILQ_FIRST(&gd->gd_tdrunq);
184 if (xtd == NULL) {
185 TAILQ_INSERT_TAIL(&gd->gd_tdrunq, td, td_threadq);
186 atomic_set_int_nonlocked(&gd->gd_reqflags, RQF_RUNNING);
187 } else {
188 while (xtd && xtd->td_pri > td->td_pri)
189 xtd = TAILQ_NEXT(xtd, td_threadq);
190 if (xtd)
191 TAILQ_INSERT_BEFORE(xtd, td, td_threadq);
192 else
193 TAILQ_INSERT_TAIL(&gd->gd_tdrunq, td, td_threadq);
194 }
195 gd->gd_fairq_total_pri += td->td_pri;
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196 }
197}
8ad65e08 198
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199static __boolean_t
200_lwkt_thread_ctor(void *obj, void *privdata, int ocflags)
201{
202 struct thread *td = (struct thread *)obj;
203
204 td->td_kstack = NULL;
205 td->td_kstack_size = 0;
206 td->td_flags = TDF_ALLOCATED_THREAD;
207 return (1);
208}
209
210static void
211_lwkt_thread_dtor(void *obj, void *privdata)
212{
213 struct thread *td = (struct thread *)obj;
214
215 KASSERT(td->td_flags & TDF_ALLOCATED_THREAD,
216 ("_lwkt_thread_dtor: not allocated from objcache"));
217 KASSERT((td->td_flags & TDF_ALLOCATED_STACK) && td->td_kstack &&
218 td->td_kstack_size > 0,
219 ("_lwkt_thread_dtor: corrupted stack"));
220 kmem_free(&kernel_map, (vm_offset_t)td->td_kstack, td->td_kstack_size);
221}
222
223/*
224 * Initialize the lwkt s/system.
225 */
226void
227lwkt_init(void)
228{
229 /* An objcache has 2 magazines per CPU so divide cache size by 2. */
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230 thread_cache = objcache_create_mbacked(M_THREAD, sizeof(struct thread),
231 NULL, CACHE_NTHREADS/2,
232 _lwkt_thread_ctor, _lwkt_thread_dtor, NULL);
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233}
234
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235/*
236 * Schedule a thread to run. As the current thread we can always safely
237 * schedule ourselves, and a shortcut procedure is provided for that
238 * function.
239 *
240 * (non-blocking, self contained on a per cpu basis)
241 */
242void
243lwkt_schedule_self(thread_t td)
244{
245 crit_enter_quick(td);
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246 KASSERT(td != &td->td_gd->gd_idlethread,
247 ("lwkt_schedule_self(): scheduling gd_idlethread is illegal!"));
9388413d 248 KKASSERT(td->td_lwp == NULL || (td->td_lwp->lwp_flag & LWP_ONRUNQ) == 0);
37af14fe 249 _lwkt_enqueue(td);
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250 crit_exit_quick(td);
251}
252
253/*
254 * Deschedule a thread.
255 *
256 * (non-blocking, self contained on a per cpu basis)
257 */
258void
259lwkt_deschedule_self(thread_t td)
260{
261 crit_enter_quick(td);
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262 _lwkt_dequeue(td);
263 crit_exit_quick(td);
264}
265
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266/*
267 * LWKTs operate on a per-cpu basis
268 *
73e4f7b9 269 * WARNING! Called from early boot, 'mycpu' may not work yet.
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270 */
271void
272lwkt_gdinit(struct globaldata *gd)
273{
f9235b6d 274 TAILQ_INIT(&gd->gd_tdrunq);
73e4f7b9 275 TAILQ_INIT(&gd->gd_tdallq);
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276}
277
278/*
7d0bac62 279 * Create a new thread. The thread must be associated with a process context
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280 * or LWKT start address before it can be scheduled. If the target cpu is
281 * -1 the thread will be created on the current cpu.
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282 *
283 * If you intend to create a thread without a process context this function
284 * does everything except load the startup and switcher function.
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285 */
286thread_t
d3d32139 287lwkt_alloc_thread(struct thread *td, int stksize, int cpu, int flags)
7d0bac62 288{
c070746a 289 globaldata_t gd = mycpu;
99df837e 290 void *stack;
7d0bac62 291
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292 /*
293 * If static thread storage is not supplied allocate a thread. Reuse
294 * a cached free thread if possible. gd_freetd is used to keep an exiting
295 * thread intact through the exit.
296 */
ef0fdad1 297 if (td == NULL) {
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MD
298 crit_enter_gd(gd);
299 if ((td = gd->gd_freetd) != NULL) {
300 KKASSERT((td->td_flags & (TDF_RUNNING|TDF_PREEMPT_LOCK|
301 TDF_RUNQ)) == 0);
c070746a 302 gd->gd_freetd = NULL;
cf709dd2 303 } else {
c070746a 304 td = objcache_get(thread_cache, M_WAITOK);
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305 KKASSERT((td->td_flags & (TDF_RUNNING|TDF_PREEMPT_LOCK|
306 TDF_RUNQ)) == 0);
307 }
308 crit_exit_gd(gd);
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309 KASSERT((td->td_flags &
310 (TDF_ALLOCATED_THREAD|TDF_RUNNING)) == TDF_ALLOCATED_THREAD,
311 ("lwkt_alloc_thread: corrupted td flags 0x%X", td->td_flags));
312 flags |= td->td_flags & (TDF_ALLOCATED_THREAD|TDF_ALLOCATED_STACK);
ef0fdad1 313 }
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314
315 /*
316 * Try to reuse cached stack.
317 */
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318 if ((stack = td->td_kstack) != NULL && td->td_kstack_size != stksize) {
319 if (flags & TDF_ALLOCATED_STACK) {
e4846942 320 kmem_free(&kernel_map, (vm_offset_t)stack, td->td_kstack_size);
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321 stack = NULL;
322 }
323 }
324 if (stack == NULL) {
e40cfbd7 325 stack = (void *)kmem_alloc_stack(&kernel_map, stksize);
ef0fdad1 326 flags |= TDF_ALLOCATED_STACK;
99df837e 327 }
75cdbe6c 328 if (cpu < 0)
c070746a 329 lwkt_init_thread(td, stack, stksize, flags, gd);
75cdbe6c 330 else
f470d0c8 331 lwkt_init_thread(td, stack, stksize, flags, globaldata_find(cpu));
99df837e 332 return(td);
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333}
334
335/*
336 * Initialize a preexisting thread structure. This function is used by
337 * lwkt_alloc_thread() and also used to initialize the per-cpu idlethread.
338 *
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339 * All threads start out in a critical section at a priority of
340 * TDPRI_KERN_DAEMON. Higher level code will modify the priority as
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341 * appropriate. This function may send an IPI message when the
342 * requested cpu is not the current cpu and consequently gd_tdallq may
343 * not be initialized synchronously from the point of view of the originating
344 * cpu.
345 *
346 * NOTE! we have to be careful in regards to creating threads for other cpus
347 * if SMP has not yet been activated.
7d0bac62 348 */
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349#ifdef SMP
350
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351static void
352lwkt_init_thread_remote(void *arg)
353{
354 thread_t td = arg;
355
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356 /*
357 * Protected by critical section held by IPI dispatch
358 */
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359 TAILQ_INSERT_TAIL(&td->td_gd->gd_tdallq, td, td_allq);
360}
361
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362#endif
363
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364/*
365 * lwkt core thread structural initialization.
366 *
367 * NOTE: All threads are initialized as mpsafe threads.
368 */
7d0bac62 369void
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370lwkt_init_thread(thread_t td, void *stack, int stksize, int flags,
371 struct globaldata *gd)
7d0bac62 372{
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373 globaldata_t mygd = mycpu;
374
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375 bzero(td, sizeof(struct thread));
376 td->td_kstack = stack;
f470d0c8 377 td->td_kstack_size = stksize;
d3d32139 378 td->td_flags = flags;
26a0694b 379 td->td_gd = gd;
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380 td->td_pri = TDPRI_KERN_DAEMON;
381 td->td_critcount = 1;
3b998fa9 382 td->td_toks_stop = &td->td_toks_base;
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383 if (lwkt_use_spin_port)
384 lwkt_initport_spin(&td->td_msgport);
385 else
386 lwkt_initport_thread(&td->td_msgport, td);
99df837e 387 pmap_init_thread(td);
0f7a3396 388#ifdef SMP
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389 /*
390 * Normally initializing a thread for a remote cpu requires sending an
391 * IPI. However, the idlethread is setup before the other cpus are
392 * activated so we have to treat it as a special case. XXX manipulation
393 * of gd_tdallq requires the BGL.
394 */
395 if (gd == mygd || td == &gd->gd_idlethread) {
37af14fe 396 crit_enter_gd(mygd);
75cdbe6c 397 TAILQ_INSERT_TAIL(&gd->gd_tdallq, td, td_allq);
37af14fe 398 crit_exit_gd(mygd);
75cdbe6c 399 } else {
2db3b277 400 lwkt_send_ipiq(gd, lwkt_init_thread_remote, td);
75cdbe6c 401 }
0f7a3396 402#else
37af14fe 403 crit_enter_gd(mygd);
0f7a3396 404 TAILQ_INSERT_TAIL(&gd->gd_tdallq, td, td_allq);
37af14fe 405 crit_exit_gd(mygd);
0f7a3396 406#endif
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407
408 dsched_new_thread(td);
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409}
410
411void
412lwkt_set_comm(thread_t td, const char *ctl, ...)
413{
e2565a42 414 __va_list va;
73e4f7b9 415
e2565a42 416 __va_start(va, ctl);
379210cb 417 kvsnprintf(td->td_comm, sizeof(td->td_comm), ctl, va);
e2565a42 418 __va_end(va);
e7c0dbba 419 KTR_LOG(ctxsw_newtd, td, &td->td_comm[0]);
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420}
421
99df837e 422void
73e4f7b9 423lwkt_hold(thread_t td)
99df837e 424{
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425 ++td->td_refs;
426}
427
428void
429lwkt_rele(thread_t td)
430{
431 KKASSERT(td->td_refs > 0);
432 --td->td_refs;
433}
434
435void
436lwkt_wait_free(thread_t td)
437{
438 while (td->td_refs)
377d4740 439 tsleep(td, 0, "tdreap", hz);
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440}
441
442void
443lwkt_free_thread(thread_t td)
444{
cf709dd2 445 KKASSERT((td->td_flags & (TDF_RUNNING|TDF_PREEMPT_LOCK|TDF_RUNQ)) == 0);
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446 if (td->td_flags & TDF_ALLOCATED_THREAD) {
447 objcache_put(thread_cache, td);
448 } else if (td->td_flags & TDF_ALLOCATED_STACK) {
449 /* client-allocated struct with internally allocated stack */
450 KASSERT(td->td_kstack && td->td_kstack_size > 0,
451 ("lwkt_free_thread: corrupted stack"));
452 kmem_free(&kernel_map, (vm_offset_t)td->td_kstack, td->td_kstack_size);
453 td->td_kstack = NULL;
454 td->td_kstack_size = 0;
99df837e 455 }
e7c0dbba 456 KTR_LOG(ctxsw_deadtd, td);
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457}
458
459
7d0bac62 460/*
8ad65e08 461 * Switch to the next runnable lwkt. If no LWKTs are runnable then
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462 * switch to the idlethread. Switching must occur within a critical
463 * section to avoid races with the scheduling queue.
464 *
465 * We always have full control over our cpu's run queue. Other cpus
466 * that wish to manipulate our queue must use the cpu_*msg() calls to
467 * talk to our cpu, so a critical section is all that is needed and
468 * the result is very, very fast thread switching.
469 *
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470 * The LWKT scheduler uses a fixed priority model and round-robins at
471 * each priority level. User process scheduling is a totally
472 * different beast and LWKT priorities should not be confused with
473 * user process priorities.
f1d1c3fa 474 *
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475 * The MP lock may be out of sync with the thread's td_mpcount + td_xpcount.
476 * lwkt_switch() cleans it up.
477 *
478 * Note that the td_switch() function cannot do anything that requires
479 * the MP lock since the MP lock will have already been setup for
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480 * the target thread (not the current thread). It's nice to have a scheduler
481 * that does not need the MP lock to work because it allows us to do some
482 * really cool high-performance MP lock optimizations.
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483 *
484 * PREEMPTION NOTE: Preemption occurs via lwkt_preempt(). lwkt_switch()
485 * is not called by the current thread in the preemption case, only when
486 * the preempting thread blocks (in order to return to the original thread).
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487 */
488void
489lwkt_switch(void)
490{
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491 globaldata_t gd = mycpu;
492 thread_t td = gd->gd_curthread;
8ad65e08 493 thread_t ntd;
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494 thread_t xtd;
495 thread_t nlast;
f9235b6d 496 int nquserok;
6f207a2c 497#ifdef SMP
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498 int mpheld;
499#endif
f9235b6d 500 int didaccumulate;
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501 const char *lmsg; /* diagnostic - 'systat -pv 1' */
502 const void *laddr;
8ad65e08 503
46a3f46d 504 /*
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505 * Switching from within a 'fast' (non thread switched) interrupt or IPI
506 * is illegal. However, we may have to do it anyway if we hit a fatal
507 * kernel trap or we have paniced.
508 *
509 * If this case occurs save and restore the interrupt nesting level.
46a3f46d 510 */
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511 if (gd->gd_intr_nesting_level) {
512 int savegdnest;
513 int savegdtrap;
514
5fddbda2 515 if (gd->gd_trap_nesting_level == 0 && panic_cpu_gd != mycpu) {
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516 panic("lwkt_switch: Attempt to switch from a "
517 "a fast interrupt, ipi, or hard code section, "
518 "td %p\n",
519 td);
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520 } else {
521 savegdnest = gd->gd_intr_nesting_level;
522 savegdtrap = gd->gd_trap_nesting_level;
523 gd->gd_intr_nesting_level = 0;
524 gd->gd_trap_nesting_level = 0;
a7422615
MD
525 if ((td->td_flags & TDF_PANICWARN) == 0) {
526 td->td_flags |= TDF_PANICWARN;
4a28fe22
MD
527 kprintf("Warning: thread switch from interrupt, IPI, "
528 "or hard code section.\n"
a7422615 529 "thread %p (%s)\n", td, td->td_comm);
7ce2998e 530 print_backtrace(-1);
a7422615 531 }
27e88a6e
MD
532 lwkt_switch();
533 gd->gd_intr_nesting_level = savegdnest;
534 gd->gd_trap_nesting_level = savegdtrap;
535 return;
536 }
96728c05 537 }
ef0fdad1 538
cb973d15
MD
539 /*
540 * Passive release (used to transition from user to kernel mode
541 * when we block or switch rather then when we enter the kernel).
542 * This function is NOT called if we are switching into a preemption
543 * or returning from a preemption. Typically this causes us to lose
0a3f9b47
MD
544 * our current process designation (if we have one) and become a true
545 * LWKT thread, and may also hand the current process designation to
546 * another process and schedule thread.
cb973d15
MD
547 */
548 if (td->td_release)
549 td->td_release(td);
550
37af14fe 551 crit_enter_gd(gd);
3b998fa9 552 if (TD_TOKS_HELD(td))
9d265729
MD
553 lwkt_relalltokens(td);
554
555 /*
b02926de
MD
556 * We had better not be holding any spin locks, but don't get into an
557 * endless panic loop.
9d265729 558 */
d666840a
MD
559 KASSERT(gd->gd_spinlocks_wr == 0 || panicstr != NULL,
560 ("lwkt_switch: still holding %d exclusive spinlocks!",
561 gd->gd_spinlocks_wr));
9d265729 562
8a8d5d85
MD
563
564#ifdef SMP
565 /*
3933a3ab
MD
566 * td_mpcount + td_xpcount cannot be used to determine if we currently
567 * hold the MP lock because get_mplock() will increment it prior to
568 * attempting to get the lock, and switch out if it can't. Our
569 * ownership of the actual lock will remain stable while we are
570 * in a critical section, and once we actually acquire the underlying
571 * lock as long as the count is greater than 0.
8a8d5d85 572 */
c5724852 573 mpheld = MP_LOCK_HELD(gd);
0f7a3396
MD
574#ifdef INVARIANTS
575 if (td->td_cscount) {
6ea70f76 576 kprintf("Diagnostic: attempt to switch while mastering cpusync: %p\n",
0f7a3396
MD
577 td);
578 if (panic_on_cscount)
579 panic("switching while mastering cpusync");
580 }
581#endif
8a8d5d85 582#endif
f9235b6d
MD
583
584 /*
585 * If we had preempted another thread on this cpu, resume the preempted
586 * thread. This occurs transparently, whether the preempted thread
587 * was scheduled or not (it may have been preempted after descheduling
588 * itself).
589 *
590 * We have to setup the MP lock for the original thread after backing
591 * out the adjustment that was made to curthread when the original
592 * was preempted.
593 */
99df837e 594 if ((ntd = td->td_preempted) != NULL) {
26a0694b 595 KKASSERT(ntd->td_flags & TDF_PREEMPT_LOCK);
8a8d5d85 596#ifdef SMP
3933a3ab 597 if (ntd->td_mpcount + ntd->td_xpcount && mpheld == 0) {
fc92d4aa 598 panic("MPLOCK NOT HELD ON RETURN: %p %p %d %d",
3933a3ab 599 td, ntd, td->td_mpcount, ntd->td_mpcount + ntd->td_xpcount);
8a8d5d85 600 }
3933a3ab 601 td->td_xpcount = 0;
8a8d5d85 602#endif
26a0694b 603 ntd->td_flags |= TDF_PREEMPT_DONE;
8ec60c3f
MD
604
605 /*
b9eb1c19
MD
606 * The interrupt may have woken a thread up, we need to properly
607 * set the reschedule flag if the originally interrupted thread is
608 * at a lower priority.
8ec60c3f 609 */
f9235b6d
MD
610 if (TAILQ_FIRST(&gd->gd_tdrunq) &&
611 TAILQ_FIRST(&gd->gd_tdrunq)->td_pri > ntd->td_pri) {
8ec60c3f 612 need_lwkt_resched();
f9235b6d 613 }
8a8d5d85 614 /* YYY release mp lock on switchback if original doesn't need it */
f9235b6d
MD
615 goto havethread_preempted;
616 }
617
618 /*
619 * Implement round-robin fairq with priority insertion. The priority
620 * insertion is handled by _lwkt_enqueue()
621 *
622 * We have to adjust the MP lock for the target thread. If we
623 * need the MP lock and cannot obtain it we try to locate a
624 * thread that does not need the MP lock. If we cannot, we spin
625 * instead of HLT.
626 *
627 * A similar issue exists for the tokens held by the target thread.
628 * If we cannot obtain ownership of the tokens we cannot immediately
629 * schedule the thread.
630 */
631 for (;;) {
632 clear_lwkt_resched();
633 didaccumulate = 0;
634 ntd = TAILQ_FIRST(&gd->gd_tdrunq);
635
4b5f931b 636 /*
f9235b6d 637 * Hotpath if we can get all necessary resources.
41a01a4d 638 *
f9235b6d 639 * If nothing is runnable switch to the idle thread
41a01a4d 640 */
f9235b6d
MD
641 if (ntd == NULL) {
642 ntd = &gd->gd_idlethread;
643 if (gd->gd_reqflags & RQF_IDLECHECK_MASK)
644 ntd->td_flags |= TDF_IDLE_NOHLT;
6f207a2c 645#ifdef SMP
3933a3ab 646 KKASSERT(ntd->td_xpcount == 0);
f9235b6d
MD
647 if (ntd->td_mpcount) {
648 if (gd->gd_trap_nesting_level == 0 && panicstr == NULL)
649 panic("Idle thread %p was holding the BGL!", ntd);
650 if (mpheld == 0) {
c5724852
MD
651 set_cpu_contention_mask(gd);
652 handle_cpu_contention_mask();
653 cpu_try_mplock();
654 mpheld = MP_LOCK_HELD(gd);
f9235b6d
MD
655 cpu_pause();
656 continue;
657 }
658 }
c5724852 659 clr_cpu_contention_mask(gd);
6f207a2c 660#endif
b37f18d6
MD
661 cpu_time.cp_msg[0] = 0;
662 cpu_time.cp_stallpc = 0;
f9235b6d
MD
663 goto haveidle;
664 }
41a01a4d
MD
665
666 /*
f9235b6d 667 * Hotpath schedule
6f207a2c
MD
668 *
669 * NOTE: For UP there is no mplock and lwkt_getalltokens()
670 * always succeeds.
8ec60c3f 671 */
f9235b6d
MD
672 if (ntd->td_fairq_accum >= 0 &&
673#ifdef SMP
3933a3ab
MD
674 (ntd->td_mpcount + ntd->td_xpcount == 0 ||
675 mpheld || cpu_try_mplock()) &&
f9235b6d 676#endif
b37f18d6 677 (!TD_TOKS_HELD(ntd) || lwkt_getalltokens(ntd, &lmsg, &laddr))
f9235b6d 678 ) {
8a8d5d85 679#ifdef SMP
c5724852 680 clr_cpu_contention_mask(gd);
f9235b6d
MD
681#endif
682 goto havethread;
683 }
684
b37f18d6
MD
685 lmsg = NULL;
686 laddr = NULL;
687
f9235b6d 688#ifdef SMP
c5724852
MD
689 if (ntd->td_fairq_accum >= 0)
690 set_cpu_contention_mask(gd);
f9235b6d 691 /* Reload mpheld (it become stale after mplock/token ops) */
c5724852 692 mpheld = MP_LOCK_HELD(gd);
3933a3ab 693 if (ntd->td_mpcount + ntd->td_xpcount && mpheld == 0) {
b37f18d6
MD
694 lmsg = "mplock";
695 laddr = ntd->td_mplock_stallpc;
696 }
f9235b6d
MD
697#endif
698
699 /*
700 * Coldpath - unable to schedule ntd, continue looking for threads
701 * to schedule. This is only allowed of the (presumably) kernel
702 * thread exhausted its fair share. A kernel thread stuck on
703 * resources does not currently allow a user thread to get in
704 * front of it.
705 */
706#ifdef SMP
707 nquserok = ((ntd->td_pri < TDPRI_KERN_LPSCHED) ||
708 (ntd->td_fairq_accum < 0));
6f207a2c
MD
709#else
710 nquserok = 1;
f9235b6d
MD
711#endif
712 nlast = NULL;
713
714 for (;;) {
41a01a4d 715 /*
f9235b6d
MD
716 * If the fair-share scheduler ran out ntd gets moved to the
717 * end and its accumulator will be bumped, if it didn't we
718 * maintain the same queue position.
df6b8ba0 719 *
f9235b6d 720 * nlast keeps track of the last element prior to any moves.
41a01a4d 721 */
f9235b6d 722 if (ntd->td_fairq_accum < 0) {
f9235b6d
MD
723 lwkt_fairq_accumulate(gd, ntd);
724 didaccumulate = 1;
c5724852
MD
725
726 /*
727 * Move to end
728 */
729 xtd = TAILQ_NEXT(ntd, td_threadq);
f9235b6d
MD
730 TAILQ_REMOVE(&gd->gd_tdrunq, ntd, td_threadq);
731 TAILQ_INSERT_TAIL(&gd->gd_tdrunq, ntd, td_threadq);
c5724852
MD
732
733 /*
734 * Set terminal element (nlast)
735 */
f9235b6d
MD
736 if (nlast == NULL) {
737 nlast = ntd;
738 if (xtd == NULL)
739 xtd = ntd;
740 }
741 ntd = xtd;
742 } else {
743 ntd = TAILQ_NEXT(ntd, td_threadq);
744 }
a453459d 745
f9235b6d
MD
746 /*
747 * If we exhausted the run list switch to the idle thread.
748 * Since one or more threads had resource acquisition issues
749 * we do not allow the idle thread to halt.
750 *
751 * NOTE: nlast can be NULL.
752 */
753 if (ntd == nlast) {
e0a90d3b 754 cpu_pause();
f9235b6d
MD
755 ntd = &gd->gd_idlethread;
756 ntd->td_flags |= TDF_IDLE_NOHLT;
6f207a2c 757#ifdef SMP
3933a3ab 758 KKASSERT(ntd->td_xpcount == 0);
f9235b6d 759 if (ntd->td_mpcount) {
c5724852 760 mpheld = MP_LOCK_HELD(gd);
f9235b6d
MD
761 if (gd->gd_trap_nesting_level == 0 && panicstr == NULL)
762 panic("Idle thread %p was holding the BGL!", ntd);
763 if (mpheld == 0) {
c5724852
MD
764 set_cpu_contention_mask(gd);
765 handle_cpu_contention_mask();
766 cpu_try_mplock();
767 mpheld = MP_LOCK_HELD(gd);
f9235b6d
MD
768 cpu_pause();
769 break; /* try again from the top, almost */
b9eb1c19 770 }
8a8d5d85 771 }
6f207a2c 772#endif
684a93c4
MD
773
774 /*
f9235b6d
MD
775 * If fairq accumulations occured we do not schedule the
776 * idle thread. This will cause us to try again from
777 * the (almost) top.
684a93c4 778 */
f9235b6d 779 if (didaccumulate)
b37f18d6
MD
780 break; /* try again from the top, almost */
781 if (lmsg)
782 strlcpy(cpu_time.cp_msg, lmsg, sizeof(cpu_time.cp_msg));
783 cpu_time.cp_stallpc = (uintptr_t)laddr;
f9235b6d 784 goto haveidle;
8a8d5d85 785 }
f9235b6d 786
df6b8ba0 787 /*
f9235b6d 788 * Try to switch to this thread.
6f207a2c
MD
789 *
790 * NOTE: For UP there is no mplock and lwkt_getalltokens()
791 * always succeeds.
df6b8ba0 792 */
77912481
MD
793 if ((ntd->td_pri >= TDPRI_KERN_LPSCHED || nquserok ||
794 user_pri_sched) && ntd->td_fairq_accum >= 0 &&
f9235b6d 795#ifdef SMP
3933a3ab
MD
796 (ntd->td_mpcount + ntd->td_xpcount == 0 ||
797 mpheld || cpu_try_mplock()) &&
8a8d5d85 798#endif
b37f18d6 799 (!TD_TOKS_HELD(ntd) || lwkt_getalltokens(ntd, &lmsg, &laddr))
f9235b6d 800 ) {
a453459d 801#ifdef SMP
c5724852 802 clr_cpu_contention_mask(gd);
f9235b6d
MD
803#endif
804 goto havethread;
df6b8ba0 805 }
f9235b6d 806#ifdef SMP
c5724852
MD
807 if (ntd->td_fairq_accum >= 0)
808 set_cpu_contention_mask(gd);
809 /*
810 * Reload mpheld (it become stale after mplock/token ops).
811 */
812 mpheld = MP_LOCK_HELD(gd);
3933a3ab 813 if (ntd->td_mpcount + ntd->td_xpcount && mpheld == 0) {
b37f18d6
MD
814 lmsg = "mplock";
815 laddr = ntd->td_mplock_stallpc;
816 }
f9235b6d
MD
817 if (ntd->td_pri >= TDPRI_KERN_LPSCHED && ntd->td_fairq_accum >= 0)
818 nquserok = 0;
a453459d 819#endif
4b5f931b 820 }
c5724852
MD
821
822 /*
823 * All threads exhausted but we can loop due to a negative
824 * accumulator.
825 *
826 * While we are looping in the scheduler be sure to service
827 * any interrupts which were made pending due to our critical
828 * section, otherwise we could livelock (e.g.) IPIs.
829 *
830 * NOTE: splz can enter and exit the mplock so mpheld is
831 * stale after this call.
832 */
833 splz_check();
834
835#ifdef SMP
836 /*
837 * Our mplock can be cached and cause other cpus to livelock
838 * if we loop due to e.g. not being able to acquire tokens.
839 */
840 if (MP_LOCK_HELD(gd))
841 cpu_rel_mplock(gd->gd_cpuid);
842 mpheld = 0;
843#endif
f1d1c3fa 844 }
8a8d5d85
MD
845
846 /*
f9235b6d
MD
847 * Do the actual switch. WARNING: mpheld is stale here.
848 *
849 * We must always decrement td_fairq_accum on non-idle threads just
850 * in case a thread never gets a tick due to being in a continuous
851 * critical section. The page-zeroing code does that.
852 *
853 * If the thread we came up with is a higher or equal priority verses
854 * the thread at the head of the queue we move our thread to the
855 * front. This way we can always check the front of the queue.
856 */
857havethread:
858 ++gd->gd_cnt.v_swtch;
859 --ntd->td_fairq_accum;
860 xtd = TAILQ_FIRST(&gd->gd_tdrunq);
861 if (ntd != xtd && ntd->td_pri >= xtd->td_pri) {
862 TAILQ_REMOVE(&gd->gd_tdrunq, ntd, td_threadq);
863 TAILQ_INSERT_HEAD(&gd->gd_tdrunq, ntd, td_threadq);
864 }
865havethread_preempted:
866 ;
867 /*
868 * If the new target does not need the MP lock and we are holding it,
869 * release the MP lock. If the new target requires the MP lock we have
870 * already acquired it for the target.
871 *
872 * WARNING: mpheld is stale here.
8a8d5d85 873 */
f9235b6d
MD
874haveidle:
875 KASSERT(ntd->td_critcount,
876 ("priority problem in lwkt_switch %d %d", td->td_pri, ntd->td_pri));
8a8d5d85 877#ifdef SMP
3933a3ab 878 if (ntd->td_mpcount + ntd->td_xpcount == 0 ) {
c5724852
MD
879 if (MP_LOCK_HELD(gd))
880 cpu_rel_mplock(gd->gd_cpuid);
8a8d5d85 881 } else {
a453459d 882 ASSERT_MP_LOCK_HELD(ntd);
8a8d5d85
MD
883 }
884#endif
94f6d86e
MD
885 if (td != ntd) {
886 ++switch_count;
a1f0fb66 887 KTR_LOG(ctxsw_sw, gd->gd_cpuid, ntd);
f1d1c3fa 888 td->td_switch(ntd);
94f6d86e 889 }
37af14fe
MD
890 /* NOTE: current cpu may have changed after switch */
891 crit_exit_quick(td);
8ad65e08
MD
892}
893
f1d1c3fa 894/*
96728c05
MD
895 * Request that the target thread preempt the current thread. Preemption
896 * only works under a specific set of conditions:
b68b7282 897 *
96728c05
MD
898 * - We are not preempting ourselves
899 * - The target thread is owned by the current cpu
900 * - We are not currently being preempted
901 * - The target is not currently being preempted
d3d1cbc8
MD
902 * - We are not holding any spin locks
903 * - The target thread is not holding any tokens
96728c05
MD
904 * - We are able to satisfy the target's MP lock requirements (if any).
905 *
906 * THE CALLER OF LWKT_PREEMPT() MUST BE IN A CRITICAL SECTION. Typically
907 * this is called via lwkt_schedule() through the td_preemptable callback.
f9235b6d 908 * critcount is the managed critical priority that we should ignore in order
96728c05
MD
909 * to determine whether preemption is possible (aka usually just the crit
910 * priority of lwkt_schedule() itself).
b68b7282 911 *
26a0694b
MD
912 * XXX at the moment we run the target thread in a critical section during
913 * the preemption in order to prevent the target from taking interrupts
914 * that *WE* can't. Preemption is strictly limited to interrupt threads
915 * and interrupt-like threads, outside of a critical section, and the
916 * preempted source thread will be resumed the instant the target blocks
917 * whether or not the source is scheduled (i.e. preemption is supposed to
918 * be as transparent as possible).
4b5f931b 919 *
8a8d5d85
MD
920 * The target thread inherits our MP count (added to its own) for the
921 * duration of the preemption in order to preserve the atomicy of the
96728c05
MD
922 * MP lock during the preemption. Therefore, any preempting targets must be
923 * careful in regards to MP assertions. Note that the MP count may be
71ef2f5c
MD
924 * out of sync with the physical mp_lock, but we do not have to preserve
925 * the original ownership of the lock if it was out of synch (that is, we
926 * can leave it synchronized on return).
b68b7282
MD
927 */
928void
f9235b6d 929lwkt_preempt(thread_t ntd, int critcount)
b68b7282 930{
46a3f46d 931 struct globaldata *gd = mycpu;
0a3f9b47 932 thread_t td;
8a8d5d85
MD
933#ifdef SMP
934 int mpheld;
57c254db 935 int savecnt;
8a8d5d85 936#endif
2d910aaf 937 int save_gd_intr_nesting_level;
b68b7282 938
26a0694b 939 /*
96728c05
MD
940 * The caller has put us in a critical section. We can only preempt
941 * if the caller of the caller was not in a critical section (basically
f9235b6d 942 * a local interrupt), as determined by the 'critcount' parameter. We
47737962 943 * also can't preempt if the caller is holding any spinlocks (even if
d666840a 944 * he isn't in a critical section). This also handles the tokens test.
96728c05
MD
945 *
946 * YYY The target thread must be in a critical section (else it must
947 * inherit our critical section? I dunno yet).
41a01a4d 948 *
0a3f9b47 949 * Set need_lwkt_resched() unconditionally for now YYY.
26a0694b 950 */
f9235b6d 951 KASSERT(ntd->td_critcount, ("BADCRIT0 %d", ntd->td_pri));
26a0694b 952
fbc024e4
MD
953 if (preempt_enable == 0) {
954 ++preempt_miss;
955 return;
956 }
957
0a3f9b47 958 td = gd->gd_curthread;
f9235b6d 959 if (ntd->td_pri <= td->td_pri) {
57c254db
MD
960 ++preempt_miss;
961 return;
962 }
f9235b6d 963 if (td->td_critcount > critcount) {
96728c05 964 ++preempt_miss;
8ec60c3f 965 need_lwkt_resched();
96728c05
MD
966 return;
967 }
968#ifdef SMP
46a3f46d 969 if (ntd->td_gd != gd) {
96728c05 970 ++preempt_miss;
8ec60c3f 971 need_lwkt_resched();
96728c05
MD
972 return;
973 }
974#endif
41a01a4d 975 /*
77912481
MD
976 * We don't have to check spinlocks here as they will also bump
977 * td_critcount.
d3d1cbc8
MD
978 *
979 * Do not try to preempt if the target thread is holding any tokens.
980 * We could try to acquire the tokens but this case is so rare there
981 * is no need to support it.
41a01a4d 982 */
77912481
MD
983 KKASSERT(gd->gd_spinlocks_wr == 0);
984
3b998fa9 985 if (TD_TOKS_HELD(ntd)) {
d3d1cbc8
MD
986 ++preempt_miss;
987 need_lwkt_resched();
988 return;
989 }
26a0694b
MD
990 if (td == ntd || ((td->td_flags | ntd->td_flags) & TDF_PREEMPT_LOCK)) {
991 ++preempt_weird;
8ec60c3f 992 need_lwkt_resched();
26a0694b
MD
993 return;
994 }
995 if (ntd->td_preempted) {
4b5f931b 996 ++preempt_hit;
8ec60c3f 997 need_lwkt_resched();
26a0694b 998 return;
b68b7282 999 }
8a8d5d85 1000#ifdef SMP
a2a5ad0d 1001 /*
3933a3ab 1002 * NOTE: An interrupt might have occured just as we were transitioning
71ef2f5c 1003 * to or from the MP lock. In this case td_mpcount will be pre-disposed
3933a3ab
MD
1004 * (non-zero) but not actually synchronized with the mp_lock itself.
1005 * We can use it to imply an MP lock requirement for the preemption but
1006 * we cannot use it to test whether we hold the MP lock or not.
a2a5ad0d 1007 */
96728c05 1008 savecnt = td->td_mpcount;
c5724852 1009 mpheld = MP_LOCK_HELD(gd);
6d9b99db 1010 ntd->td_xpcount = td->td_mpcount + td->td_xpcount;
3933a3ab
MD
1011 if (mpheld == 0 && ntd->td_mpcount + ntd->td_xpcount && !cpu_try_mplock()) {
1012 ntd->td_xpcount = 0;
8a8d5d85 1013 ++preempt_miss;
8ec60c3f 1014 need_lwkt_resched();
8a8d5d85
MD
1015 return;
1016 }
1017#endif
26a0694b 1018
8ec60c3f
MD
1019 /*
1020 * Since we are able to preempt the current thread, there is no need to
1021 * call need_lwkt_resched().
2d910aaf
MD
1022 *
1023 * We must temporarily clear gd_intr_nesting_level around the switch
1024 * since switchouts from the target thread are allowed (they will just
1025 * return to our thread), and since the target thread has its own stack.
8ec60c3f 1026 */
26a0694b
MD
1027 ++preempt_hit;
1028 ntd->td_preempted = td;
1029 td->td_flags |= TDF_PREEMPT_LOCK;
a1f0fb66 1030 KTR_LOG(ctxsw_pre, gd->gd_cpuid, ntd);
2d910aaf
MD
1031 save_gd_intr_nesting_level = gd->gd_intr_nesting_level;
1032 gd->gd_intr_nesting_level = 0;
26a0694b 1033 td->td_switch(ntd);
2d910aaf 1034 gd->gd_intr_nesting_level = save_gd_intr_nesting_level;
b9eb1c19 1035
26a0694b 1036 KKASSERT(ntd->td_preempted && (td->td_flags & TDF_PREEMPT_DONE));
96728c05
MD
1037#ifdef SMP
1038 KKASSERT(savecnt == td->td_mpcount);
c5724852 1039 mpheld = MP_LOCK_HELD(gd);
71ef2f5c 1040 if (mpheld && td->td_mpcount == 0)
c5724852 1041 cpu_rel_mplock(gd->gd_cpuid);
3933a3ab 1042 else if (mpheld == 0 && td->td_mpcount + td->td_xpcount)
96728c05
MD
1043 panic("lwkt_preempt(): MP lock was not held through");
1044#endif
26a0694b
MD
1045 ntd->td_preempted = NULL;
1046 td->td_flags &= ~(TDF_PREEMPT_LOCK|TDF_PREEMPT_DONE);
b68b7282
MD
1047}
1048
1049/*
faaeffac 1050 * Conditionally call splz() if gd_reqflags indicates work is pending.
4a28fe22
MD
1051 * This will work inside a critical section but not inside a hard code
1052 * section.
ef0fdad1 1053 *
f1d1c3fa
MD
1054 * (self contained on a per cpu basis)
1055 */
1056void
faaeffac 1057splz_check(void)
f1d1c3fa 1058{
7966cb69
MD
1059 globaldata_t gd = mycpu;
1060 thread_t td = gd->gd_curthread;
ef0fdad1 1061
4a28fe22
MD
1062 if ((gd->gd_reqflags & RQF_IDLECHECK_MASK) &&
1063 gd->gd_intr_nesting_level == 0 &&
1064 td->td_nest_count < 2)
1065 {
f1d1c3fa 1066 splz();
4a28fe22
MD
1067 }
1068}
1069
1070/*
1071 * This version is integrated into crit_exit, reqflags has already
1072 * been tested but td_critcount has not.
1073 *
1074 * We only want to execute the splz() on the 1->0 transition of
1075 * critcount and not in a hard code section or if too deeply nested.
1076 */
1077void
1078lwkt_maybe_splz(thread_t td)
1079{
1080 globaldata_t gd = td->td_gd;
1081
1082 if (td->td_critcount == 0 &&
1083 gd->gd_intr_nesting_level == 0 &&
1084 td->td_nest_count < 2)
1085 {
1086 splz();
1087 }
f1d1c3fa
MD
1088}
1089
8ad65e08 1090/*
f9235b6d
MD
1091 * This function is used to negotiate a passive release of the current
1092 * process/lwp designation with the user scheduler, allowing the user
1093 * scheduler to schedule another user thread. The related kernel thread
1094 * (curthread) continues running in the released state.
8ad65e08
MD
1095 */
1096void
f9235b6d 1097lwkt_passive_release(struct thread *td)
8ad65e08 1098{
f9235b6d
MD
1099 struct lwp *lp = td->td_lwp;
1100
1101 td->td_release = NULL;
1102 lwkt_setpri_self(TDPRI_KERN_USER);
1103 lp->lwp_proc->p_usched->release_curproc(lp);
f1d1c3fa
MD
1104}
1105
f9235b6d 1106
f1d1c3fa 1107/*
f9235b6d
MD
1108 * This implements a normal yield. This routine is virtually a nop if
1109 * there is nothing to yield to but it will always run any pending interrupts
1110 * if called from a critical section.
1111 *
1112 * This yield is designed for kernel threads without a user context.
1113 *
1114 * (self contained on a per cpu basis)
3824f392
MD
1115 */
1116void
f9235b6d 1117lwkt_yield(void)
3824f392 1118{
f9235b6d
MD
1119 globaldata_t gd = mycpu;
1120 thread_t td = gd->gd_curthread;
1121 thread_t xtd;
3824f392 1122
f9235b6d
MD
1123 if ((gd->gd_reqflags & RQF_IDLECHECK_MASK) && td->td_nest_count < 2)
1124 splz();
1125 if (td->td_fairq_accum < 0) {
1126 lwkt_schedule_self(curthread);
1127 lwkt_switch();
1128 } else {
1129 xtd = TAILQ_FIRST(&gd->gd_tdrunq);
1130 if (xtd && xtd->td_pri > td->td_pri) {
1131 lwkt_schedule_self(curthread);
1132 lwkt_switch();
1133 }
1134 }
3824f392
MD
1135}
1136
1137/*
f9235b6d
MD
1138 * This yield is designed for kernel threads with a user context.
1139 *
1140 * The kernel acting on behalf of the user is potentially cpu-bound,
1141 * this function will efficiently allow other threads to run and also
1142 * switch to other processes by releasing.
3824f392
MD
1143 *
1144 * The lwkt_user_yield() function is designed to have very low overhead
1145 * if no yield is determined to be needed.
1146 */
1147void
1148lwkt_user_yield(void)
1149{
f9235b6d
MD
1150 globaldata_t gd = mycpu;
1151 thread_t td = gd->gd_curthread;
1152
1153 /*
1154 * Always run any pending interrupts in case we are in a critical
1155 * section.
1156 */
1157 if ((gd->gd_reqflags & RQF_IDLECHECK_MASK) && td->td_nest_count < 2)
1158 splz();
3824f392
MD
1159
1160#ifdef SMP
1161 /*
1162 * XXX SEVERE TEMPORARY HACK. A cpu-bound operation running in the
1163 * kernel can prevent other cpus from servicing interrupt threads
1164 * which still require the MP lock (which is a lot of them). This
1165 * has a chaining effect since if the interrupt is blocked, so is
1166 * the event, so normal scheduling will not pick up on the problem.
1167 */
3933a3ab 1168 if (cpu_contention_mask && td->td_mpcount + td->td_xpcount) {
684a93c4 1169 yield_mplock(td);
3824f392
MD
1170 }
1171#endif
1172
1173 /*
f9235b6d
MD
1174 * Switch (which forces a release) if another kernel thread needs
1175 * the cpu, if userland wants us to resched, or if our kernel
1176 * quantum has run out.
3824f392 1177 */
f9235b6d
MD
1178 if (lwkt_resched_wanted() ||
1179 user_resched_wanted() ||
1180 td->td_fairq_accum < 0)
1181 {
3824f392 1182 lwkt_switch();
3824f392
MD
1183 }
1184
f9235b6d 1185#if 0
3824f392 1186 /*
f9235b6d
MD
1187 * Reacquire the current process if we are released.
1188 *
1189 * XXX not implemented atm. The kernel may be holding locks and such,
1190 * so we want the thread to continue to receive cpu.
3824f392 1191 */
f9235b6d
MD
1192 if (td->td_release == NULL && lp) {
1193 lp->lwp_proc->p_usched->acquire_curproc(lp);
1194 td->td_release = lwkt_passive_release;
1195 lwkt_setpri_self(TDPRI_USER_NORM);
3824f392 1196 }
f9235b6d 1197#endif
b9eb1c19
MD
1198}
1199
1200/*
f1d1c3fa
MD
1201 * Generic schedule. Possibly schedule threads belonging to other cpus and
1202 * deal with threads that might be blocked on a wait queue.
1203 *
0a3f9b47
MD
1204 * We have a little helper inline function which does additional work after
1205 * the thread has been enqueued, including dealing with preemption and
1206 * setting need_lwkt_resched() (which prevents the kernel from returning
1207 * to userland until it has processed higher priority threads).
6330a558
MD
1208 *
1209 * It is possible for this routine to be called after a failed _enqueue
1210 * (due to the target thread migrating, sleeping, or otherwise blocked).
1211 * We have to check that the thread is actually on the run queue!
361d01dd
MD
1212 *
1213 * reschedok is an optimized constant propagated from lwkt_schedule() or
1214 * lwkt_schedule_noresched(). By default it is non-zero, causing a
1215 * reschedule to be requested if the target thread has a higher priority.
1216 * The port messaging code will set MSG_NORESCHED and cause reschedok to
1217 * be 0, prevented undesired reschedules.
8ad65e08 1218 */
0a3f9b47
MD
1219static __inline
1220void
f9235b6d 1221_lwkt_schedule_post(globaldata_t gd, thread_t ntd, int ccount, int reschedok)
0a3f9b47 1222{
b9eb1c19 1223 thread_t otd;
c730be20 1224
6330a558 1225 if (ntd->td_flags & TDF_RUNQ) {
361d01dd 1226 if (ntd->td_preemptable && reschedok) {
f9235b6d 1227 ntd->td_preemptable(ntd, ccount); /* YYY +token */
361d01dd 1228 } else if (reschedok) {
b9eb1c19 1229 otd = curthread;
f9235b6d 1230 if (ntd->td_pri > otd->td_pri)
c730be20 1231 need_lwkt_resched();
6330a558 1232 }
f9235b6d
MD
1233
1234 /*
1235 * Give the thread a little fair share scheduler bump if it
1236 * has been asleep for a while. This is primarily to avoid
1237 * a degenerate case for interrupt threads where accumulator
1238 * crosses into negative territory unnecessarily.
1239 */
1240 if (ntd->td_fairq_lticks != ticks) {
1241 ntd->td_fairq_lticks = ticks;
1242 ntd->td_fairq_accum += gd->gd_fairq_total_pri;
1243 if (ntd->td_fairq_accum > TDFAIRQ_MAX(gd))
1244 ntd->td_fairq_accum = TDFAIRQ_MAX(gd);
1245 }
0a3f9b47
MD
1246 }
1247}
1248
361d01dd 1249static __inline
8ad65e08 1250void
361d01dd 1251_lwkt_schedule(thread_t td, int reschedok)
8ad65e08 1252{
37af14fe
MD
1253 globaldata_t mygd = mycpu;
1254
cf709dd2
MD
1255 KASSERT(td != &td->td_gd->gd_idlethread,
1256 ("lwkt_schedule(): scheduling gd_idlethread is illegal!"));
37af14fe 1257 crit_enter_gd(mygd);
9388413d 1258 KKASSERT(td->td_lwp == NULL || (td->td_lwp->lwp_flag & LWP_ONRUNQ) == 0);
37af14fe 1259 if (td == mygd->gd_curthread) {
f1d1c3fa
MD
1260 _lwkt_enqueue(td);
1261 } else {
f1d1c3fa 1262 /*
7cd8d145
MD
1263 * If we own the thread, there is no race (since we are in a
1264 * critical section). If we do not own the thread there might
1265 * be a race but the target cpu will deal with it.
f1d1c3fa 1266 */
0f7a3396 1267#ifdef SMP
7cd8d145 1268 if (td->td_gd == mygd) {
9d265729 1269 _lwkt_enqueue(td);
f9235b6d 1270 _lwkt_schedule_post(mygd, td, 1, reschedok);
f1d1c3fa 1271 } else {
e381e77c 1272 lwkt_send_ipiq3(td->td_gd, lwkt_schedule_remote, td, 0);
7cd8d145 1273 }
0f7a3396 1274#else
7cd8d145 1275 _lwkt_enqueue(td);
f9235b6d 1276 _lwkt_schedule_post(mygd, td, 1, reschedok);
0f7a3396 1277#endif
8ad65e08 1278 }
37af14fe 1279 crit_exit_gd(mygd);
8ad65e08
MD
1280}
1281
361d01dd
MD
1282void
1283lwkt_schedule(thread_t td)
1284{
1285 _lwkt_schedule(td, 1);
1286}
1287
1288void
1289lwkt_schedule_noresched(thread_t td)
1290{
1291 _lwkt_schedule(td, 0);
1292}
1293
88ebb169
SW
1294#ifdef SMP
1295
e381e77c
MD
1296/*
1297 * When scheduled remotely if frame != NULL the IPIQ is being
1298 * run via doreti or an interrupt then preemption can be allowed.
1299 *
1300 * To allow preemption we have to drop the critical section so only
1301 * one is present in _lwkt_schedule_post.
1302 */
1303static void
1304lwkt_schedule_remote(void *arg, int arg2, struct intrframe *frame)
1305{
1306 thread_t td = curthread;
1307 thread_t ntd = arg;
1308
1309 if (frame && ntd->td_preemptable) {
1310 crit_exit_noyield(td);
1311 _lwkt_schedule(ntd, 1);
1312 crit_enter_quick(td);
1313 } else {
1314 _lwkt_schedule(ntd, 1);
1315 }
1316}
1317
d9eea1a5 1318/*
52eedfb5
MD
1319 * Thread migration using a 'Pull' method. The thread may or may not be
1320 * the current thread. It MUST be descheduled and in a stable state.
1321 * lwkt_giveaway() must be called on the cpu owning the thread.
1322 *
1323 * At any point after lwkt_giveaway() is called, the target cpu may
1324 * 'pull' the thread by calling lwkt_acquire().
1325 *
ae8e83e6
MD
1326 * We have to make sure the thread is not sitting on a per-cpu tsleep
1327 * queue or it will blow up when it moves to another cpu.
1328 *
52eedfb5 1329 * MPSAFE - must be called under very specific conditions.
d9eea1a5 1330 */
a2a5ad0d 1331void
52eedfb5
MD
1332lwkt_giveaway(thread_t td)
1333{
3b4192fb 1334 globaldata_t gd = mycpu;
52eedfb5 1335
3b4192fb
MD
1336 crit_enter_gd(gd);
1337 if (td->td_flags & TDF_TSLEEPQ)
1338 tsleep_remove(td);
1339 KKASSERT(td->td_gd == gd);
1340 TAILQ_REMOVE(&gd->gd_tdallq, td, td_allq);
1341 td->td_flags |= TDF_MIGRATING;
1342 crit_exit_gd(gd);
52eedfb5
MD
1343}
1344
1345void
a2a5ad0d
MD
1346lwkt_acquire(thread_t td)
1347{
37af14fe
MD
1348 globaldata_t gd;
1349 globaldata_t mygd;
a2a5ad0d 1350
52eedfb5 1351 KKASSERT(td->td_flags & TDF_MIGRATING);
a2a5ad0d 1352 gd = td->td_gd;
37af14fe 1353 mygd = mycpu;
52eedfb5 1354 if (gd != mycpu) {
35238fa5 1355 cpu_lfence();
52eedfb5 1356 KKASSERT((td->td_flags & TDF_RUNQ) == 0);
37af14fe 1357 crit_enter_gd(mygd);
df910c23
MD
1358 while (td->td_flags & (TDF_RUNNING|TDF_PREEMPT_LOCK)) {
1359#ifdef SMP
1360 lwkt_process_ipiq();
1361#endif
52eedfb5 1362 cpu_lfence();
df910c23 1363 }
562273ea 1364 cpu_mfence();
37af14fe 1365 td->td_gd = mygd;
52eedfb5
MD
1366 TAILQ_INSERT_TAIL(&mygd->gd_tdallq, td, td_allq);
1367 td->td_flags &= ~TDF_MIGRATING;
1368 crit_exit_gd(mygd);
1369 } else {
1370 crit_enter_gd(mygd);
1371 TAILQ_INSERT_TAIL(&mygd->gd_tdallq, td, td_allq);
1372 td->td_flags &= ~TDF_MIGRATING;
37af14fe 1373 crit_exit_gd(mygd);
a2a5ad0d
MD
1374 }
1375}
1376
52eedfb5
MD
1377#endif
1378
8ad65e08 1379/*
f1d1c3fa
MD
1380 * Generic deschedule. Descheduling threads other then your own should be
1381 * done only in carefully controlled circumstances. Descheduling is
1382 * asynchronous.
1383 *
1384 * This function may block if the cpu has run out of messages.
8ad65e08
MD
1385 */
1386void
1387lwkt_deschedule(thread_t td)
1388{
f1d1c3fa 1389 crit_enter();
b8a98473 1390#ifdef SMP
f1d1c3fa
MD
1391 if (td == curthread) {
1392 _lwkt_dequeue(td);
1393 } else {
a72187e9 1394 if (td->td_gd == mycpu) {
f1d1c3fa
MD
1395 _lwkt_dequeue(td);
1396 } else {
b8a98473 1397 lwkt_send_ipiq(td->td_gd, (ipifunc1_t)lwkt_deschedule, td);
f1d1c3fa
MD
1398 }
1399 }
b8a98473
MD
1400#else
1401 _lwkt_dequeue(td);
1402#endif
f1d1c3fa
MD
1403 crit_exit();
1404}
1405
1406/*
4b5f931b
MD
1407 * Set the target thread's priority. This routine does not automatically
1408 * switch to a higher priority thread, LWKT threads are not designed for
1409 * continuous priority changes. Yield if you want to switch.
4b5f931b
MD
1410 */
1411void
1412lwkt_setpri(thread_t td, int pri)
1413{
a72187e9 1414 KKASSERT(td->td_gd == mycpu);
f9235b6d
MD
1415 if (td->td_pri != pri) {
1416 KKASSERT(pri >= 0);
1417 crit_enter();
1418 if (td->td_flags & TDF_RUNQ) {
1419 _lwkt_dequeue(td);
1420 td->td_pri = pri;
1421 _lwkt_enqueue(td);
1422 } else {
1423 td->td_pri = pri;
1424 }
1425 crit_exit();
26a0694b 1426 }
26a0694b
MD
1427}
1428
03bd0a5e
MD
1429/*
1430 * Set the initial priority for a thread prior to it being scheduled for
1431 * the first time. The thread MUST NOT be scheduled before or during
1432 * this call. The thread may be assigned to a cpu other then the current
1433 * cpu.
1434 *
1435 * Typically used after a thread has been created with TDF_STOPPREQ,
1436 * and before the thread is initially scheduled.
1437 */
1438void
1439lwkt_setpri_initial(thread_t td, int pri)
1440{
1441 KKASSERT(pri >= 0);
1442 KKASSERT((td->td_flags & TDF_RUNQ) == 0);
f9235b6d 1443 td->td_pri = pri;
03bd0a5e
MD
1444}
1445
26a0694b
MD
1446void
1447lwkt_setpri_self(int pri)
1448{
1449 thread_t td = curthread;
1450
4b5f931b
MD
1451 KKASSERT(pri >= 0 && pri <= TDPRI_MAX);
1452 crit_enter();
1453 if (td->td_flags & TDF_RUNQ) {
1454 _lwkt_dequeue(td);
f9235b6d 1455 td->td_pri = pri;
4b5f931b
MD
1456 _lwkt_enqueue(td);
1457 } else {
f9235b6d 1458 td->td_pri = pri;
4b5f931b
MD
1459 }
1460 crit_exit();
1461}
1462
5d21b981 1463/*
f9235b6d
MD
1464 * 1/hz tick (typically 10ms) x TDFAIRQ_SCALE (typ 8) = 80ms full cycle.
1465 *
1466 * Example: two competing threads, same priority N. decrement by (2*N)
1467 * increment by N*8, each thread will get 4 ticks.
1468 */
1469void
1470lwkt_fairq_schedulerclock(thread_t td)
1471{
1472 if (fairq_enable) {
1473 while (td) {
1474 if (td != &td->td_gd->gd_idlethread) {
1475 td->td_fairq_accum -= td->td_gd->gd_fairq_total_pri;
1476 if (td->td_fairq_accum < -TDFAIRQ_MAX(td->td_gd))
1477 td->td_fairq_accum = -TDFAIRQ_MAX(td->td_gd);
1478 if (td->td_fairq_accum < 0)
1479 need_lwkt_resched();
1480 td->td_fairq_lticks = ticks;
1481 }
1482 td = td->td_preempted;
1483 }
1484 }
1485}
1486
1487static void
1488lwkt_fairq_accumulate(globaldata_t gd, thread_t td)
1489{
1490 td->td_fairq_accum += td->td_pri * TDFAIRQ_SCALE;
1491 if (td->td_fairq_accum > TDFAIRQ_MAX(td->td_gd))
1492 td->td_fairq_accum = TDFAIRQ_MAX(td->td_gd);
1493}
1494
1495/*
52eedfb5
MD
1496 * Migrate the current thread to the specified cpu.
1497 *
1498 * This is accomplished by descheduling ourselves from the current cpu,
1499 * moving our thread to the tdallq of the target cpu, IPI messaging the
1500 * target cpu, and switching out. TDF_MIGRATING prevents scheduling
1501 * races while the thread is being migrated.
ae8e83e6
MD
1502 *
1503 * We must be sure to remove ourselves from the current cpu's tsleepq
1504 * before potentially moving to another queue. The thread can be on
1505 * a tsleepq due to a left-over tsleep_interlock().
5d21b981 1506 */
3d28ff59 1507#ifdef SMP
5d21b981 1508static void lwkt_setcpu_remote(void *arg);
3d28ff59 1509#endif
5d21b981
MD
1510
1511void
1512lwkt_setcpu_self(globaldata_t rgd)
1513{
1514#ifdef SMP
1515 thread_t td = curthread;
1516
1517 if (td->td_gd != rgd) {
1518 crit_enter_quick(td);
ae8e83e6 1519 if (td->td_flags & TDF_TSLEEPQ)
3b4192fb 1520 tsleep_remove(td);
5d21b981
MD
1521 td->td_flags |= TDF_MIGRATING;
1522 lwkt_deschedule_self(td);
52eedfb5 1523 TAILQ_REMOVE(&td->td_gd->gd_tdallq, td, td_allq);
b8a98473 1524 lwkt_send_ipiq(rgd, (ipifunc1_t)lwkt_setcpu_remote, td);
5d21b981
MD
1525 lwkt_switch();
1526 /* we are now on the target cpu */
52eedfb5 1527 TAILQ_INSERT_TAIL(&rgd->gd_tdallq, td, td_allq);
5d21b981
MD
1528 crit_exit_quick(td);
1529 }
1530#endif
1531}
1532
ecdefdda
MD
1533void
1534lwkt_migratecpu(int cpuid)
1535{
1536#ifdef SMP
1537 globaldata_t rgd;
1538
1539 rgd = globaldata_find(cpuid);
1540 lwkt_setcpu_self(rgd);
1541#endif
1542}
1543
5d21b981
MD
1544/*
1545 * Remote IPI for cpu migration (called while in a critical section so we
1546 * do not have to enter another one). The thread has already been moved to
1547 * our cpu's allq, but we must wait for the thread to be completely switched
1548 * out on the originating cpu before we schedule it on ours or the stack
1549 * state may be corrupt. We clear TDF_MIGRATING after flushing the GD
1550 * change to main memory.
1551 *
1552 * XXX The use of TDF_MIGRATING might not be sufficient to avoid races
1553 * against wakeups. It is best if this interface is used only when there
1554 * are no pending events that might try to schedule the thread.
1555 */
3d28ff59 1556#ifdef SMP
5d21b981
MD
1557static void
1558lwkt_setcpu_remote(void *arg)
1559{
1560 thread_t td = arg;
1561 globaldata_t gd = mycpu;
1562
df910c23
MD
1563 while (td->td_flags & (TDF_RUNNING|TDF_PREEMPT_LOCK)) {
1564#ifdef SMP
1565 lwkt_process_ipiq();
1566#endif
35238fa5 1567 cpu_lfence();
562273ea 1568 cpu_pause();
df910c23 1569 }
5d21b981 1570 td->td_gd = gd;
562273ea 1571 cpu_mfence();
5d21b981 1572 td->td_flags &= ~TDF_MIGRATING;
9388413d 1573 KKASSERT(td->td_lwp == NULL || (td->td_lwp->lwp_flag & LWP_ONRUNQ) == 0);
5d21b981
MD
1574 _lwkt_enqueue(td);
1575}
3d28ff59 1576#endif
5d21b981 1577
553ea3c8 1578struct lwp *
4b5f931b
MD
1579lwkt_preempted_proc(void)
1580{
73e4f7b9 1581 thread_t td = curthread;
4b5f931b
MD
1582 while (td->td_preempted)
1583 td = td->td_preempted;
553ea3c8 1584 return(td->td_lwp);
4b5f931b
MD
1585}
1586
4b5f931b 1587/*
99df837e
MD
1588 * Create a kernel process/thread/whatever. It shares it's address space
1589 * with proc0 - ie: kernel only.
1590 *
365fa13f
MD
1591 * NOTE! By default new threads are created with the MP lock held. A
1592 * thread which does not require the MP lock should release it by calling
1593 * rel_mplock() at the start of the new thread.
99df837e
MD
1594 */
1595int
c9e9fb21
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1596lwkt_create(void (*func)(void *), void *arg, struct thread **tdp,
1597 thread_t template, int tdflags, int cpu, const char *fmt, ...)
99df837e 1598{
73e4f7b9 1599 thread_t td;
e2565a42 1600 __va_list ap;
99df837e 1601
d3d32139 1602 td = lwkt_alloc_thread(template, LWKT_THREAD_STACK, cpu,
dbcd0c9b 1603 tdflags);
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1604 if (tdp)
1605 *tdp = td;
709799ea 1606 cpu_set_thread_handler(td, lwkt_exit, func, arg);
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1607
1608 /*
1609 * Set up arg0 for 'ps' etc
1610 */
e2565a42 1611 __va_start(ap, fmt);
379210cb 1612 kvsnprintf(td->td_comm, sizeof(td->td_comm), fmt, ap);
e2565a42 1613 __va_end(ap);
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1614
1615 /*
1616 * Schedule the thread to run
1617 */
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1618 if ((td->td_flags & TDF_STOPREQ) == 0)
1619 lwkt_schedule(td);
1620 else
1621 td->td_flags &= ~TDF_STOPREQ;
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1622 return 0;
1623}
1624
1625/*
1626 * Destroy an LWKT thread. Warning! This function is not called when
1627 * a process exits, cpu_proc_exit() directly calls cpu_thread_exit() and
1628 * uses a different reaping mechanism.
1629 */
1630void
1631lwkt_exit(void)
1632{
1633 thread_t td = curthread;
c070746a 1634 thread_t std;
8826f33a 1635 globaldata_t gd;
99df837e 1636
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1637 /*
1638 * Do any cleanup that might block here
1639 */
99df837e 1640 if (td->td_flags & TDF_VERBOSE)
6ea70f76 1641 kprintf("kthread %p %s has exited\n", td, td->td_comm);
f6bf3af1 1642 caps_exit(td);
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1643 biosched_done(td);
1644 dsched_exit_thread(td);
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1645
1646 /*
1647 * Get us into a critical section to interlock gd_freetd and loop
1648 * until we can get it freed.
1649 *
1650 * We have to cache the current td in gd_freetd because objcache_put()ing
1651 * it would rip it out from under us while our thread is still active.
1652 */
1653 gd = mycpu;
37af14fe 1654 crit_enter_quick(td);
c070746a 1655 while ((std = gd->gd_freetd) != NULL) {
cf709dd2 1656 KKASSERT((std->td_flags & (TDF_RUNNING|TDF_PREEMPT_LOCK)) == 0);
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1657 gd->gd_freetd = NULL;
1658 objcache_put(thread_cache, std);
1659 }
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1660
1661 /*
1662 * Remove thread resources from kernel lists and deschedule us for
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1663 * the last time. We cannot block after this point or we may end
1664 * up with a stale td on the tsleepq.
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1665 */
1666 if (td->td_flags & TDF_TSLEEPQ)
1667 tsleep_remove(td);
37af14fe 1668 lwkt_deschedule_self(td);
e56e4dea 1669 lwkt_remove_tdallq(td);
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1670
1671 /*
1672 * Final cleanup
1673 */
1674 KKASSERT(gd->gd_freetd == NULL);
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1675 if (td->td_flags & TDF_ALLOCATED_THREAD)
1676 gd->gd_freetd = td;
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1677 cpu_thread_exit();
1678}
1679
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1680void
1681lwkt_remove_tdallq(thread_t td)
1682{
1683 KKASSERT(td->td_gd == mycpu);
1684 TAILQ_REMOVE(&td->td_gd->gd_tdallq, td, td_allq);
1685}
1686
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1687/*
1688 * Code reduction and branch prediction improvements. Call/return
1689 * overhead on modern cpus often degenerates into 0 cycles due to
1690 * the cpu's branch prediction hardware and return pc cache. We
1691 * can take advantage of this by not inlining medium-complexity
1692 * functions and we can also reduce the branch prediction impact
1693 * by collapsing perfectly predictable branches into a single
1694 * procedure instead of duplicating it.
1695 *
1696 * Is any of this noticeable? Probably not, so I'll take the
1697 * smaller code size.
1698 */
1699void
b6468f56 1700crit_exit_wrapper(__DEBUG_CRIT_ARG__)
9cf43f91 1701{
b6468f56 1702 _crit_exit(mycpu __DEBUG_CRIT_PASS_ARG__);
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1703}
1704
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1705void
1706crit_panic(void)
1707{
1708 thread_t td = curthread;
850634cc 1709 int lcrit = td->td_critcount;
2d93b37a 1710
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1711 td->td_critcount = 0;
1712 panic("td_critcount is/would-go negative! %p %d", td, lcrit);
4a28fe22 1713 /* NOT REACHED */
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1714}
1715
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1716#ifdef SMP
1717
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1718/*
1719 * Called from debugger/panic on cpus which have been stopped. We must still
1720 * process the IPIQ while stopped, even if we were stopped while in a critical
1721 * section (XXX).
1722 *
1723 * If we are dumping also try to process any pending interrupts. This may
1724 * or may not work depending on the state of the cpu at the point it was
1725 * stopped.
1726 */
1727void
1728lwkt_smp_stopped(void)
1729{
1730 globaldata_t gd = mycpu;
1731
1732 crit_enter_gd(gd);
1733 if (dumping) {
1734 lwkt_process_ipiq();
1735 splz();
1736 } else {
1737 lwkt_process_ipiq();
1738 }
1739 crit_exit_gd(gd);
1740}
1741
d165e668 1742#endif