2 * Copyright (c) 1982, 1986, 1993
3 * The Regents of the University of California. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * @(#)subr_prof.c 8.3 (Berkeley) 9/23/93
30 * $FreeBSD: src/sys/kern/subr_prof.c,v 1.32.2.2 2000/08/03 00:09:32 ps Exp $
33 #include <sys/param.h>
34 #include <sys/systm.h>
35 #include <sys/sysproto.h>
36 #include <sys/kernel.h>
38 #include <sys/resourcevar.h>
39 #include <sys/sysctl.h>
41 #include <sys/thread2.h>
43 #include <machine/cpu.h>
46 #include <sys/malloc.h>
50 static MALLOC_DEFINE(M_GPROF, "gprof", "kernel profiling buffer");
52 static void kmstartup (void *);
53 SYSINIT(kmem, SI_SUB_KPROF, SI_ORDER_FIRST, kmstartup, NULL);
55 struct gmonparam _gmonparam = { GMON_PROF_OFF };
58 #include <machine/asmacros.h>
61 nullfunc_loop_profiled(void)
65 for (i = 0; i < CALIB_SCALE; i++)
69 #define nullfunc_loop_profiled_end nullfunc_profiled /* XXX */
72 nullfunc_profiled(void)
78 kmstartup(void *dummy)
81 struct gmonparam *p = &_gmonparam;
87 int mexitcount_overhead;
88 int nullfunc_loop_overhead;
89 int nullfunc_loop_profiled_time;
94 * Round lowpc and highpc to multiples of the density we're using
95 * so the rest of the scaling (here and in gprof) stays in ints.
97 p->lowpc = ROUNDDOWN((u_long)btext, HISTFRACTION * sizeof(HISTCOUNTER));
98 p->highpc = ROUNDUP((u_long)etext, HISTFRACTION * sizeof(HISTCOUNTER));
99 p->textsize = p->highpc - p->lowpc;
100 kprintf("Profiling kernel, textsize=%lu [%jx..%jx]\n",
101 p->textsize, (uintmax_t)p->lowpc, (uintmax_t)p->highpc);
102 p->kcountsize = p->textsize / HISTFRACTION;
103 p->hashfraction = HASHFRACTION;
104 p->fromssize = p->textsize / HASHFRACTION;
105 p->tolimit = p->textsize * ARCDENSITY / 100;
106 if (p->tolimit < MINARCS)
107 p->tolimit = MINARCS;
108 else if (p->tolimit > MAXARCS)
109 p->tolimit = MAXARCS;
110 p->tossize = p->tolimit * sizeof(struct tostruct);
111 cp = (char *)kmalloc(p->kcountsize + p->fromssize + p->tossize,
112 M_GPROF, M_NOWAIT | M_ZERO);
114 kprintf("No memory for profiling.\n");
117 p->tos = (struct tostruct *)cp;
119 p->kcount = (HISTCOUNTER *)cp;
121 p->froms = (u_short *)cp;
124 /* Initialize pointers to overhead counters. */
125 p->cputime_count = &KCOUNT(p, PC_TO_I(p, cputime));
126 p->mcount_count = &KCOUNT(p, PC_TO_I(p, mcount));
127 p->mexitcount_count = &KCOUNT(p, PC_TO_I(p, mexitcount));
130 * Disable interrupts to avoid interference while we calibrate
136 * Determine overheads.
137 * XXX this needs to be repeated for each useful timer/counter.
139 cputime_overhead = 0;
141 for (i = 0; i < CALIB_SCALE; i++)
142 cputime_overhead += cputime();
147 empty_loop_time = cputime();
149 nullfunc_loop_profiled();
152 * Start profiling. There won't be any normal function calls since
153 * interrupts are disabled, but we will call the profiling routines
154 * directly to determine their overheads.
156 p->state = GMON_PROF_HIRES;
159 nullfunc_loop_profiled();
162 for (i = 0; i < CALIB_SCALE; i++)
163 #if defined(__i386__) && __GNUC__ >= 2
164 __asm("pushl %0; call __mcount; popl %%ecx"
167 : "ax", "bx", "cx", "dx", "memory");
171 mcount_overhead = KCOUNT(p, PC_TO_I(p, profil));
174 for (i = 0; i < CALIB_SCALE; i++)
175 #if defined(__i386__) && __GNUC__ >= 2
176 __asm("call " __XSTRING(HIDENAME(mexitcount)) "; 1:"
177 : : : "ax", "bx", "cx", "dx", "memory");
178 __asm("movl $1b,%0" : "=rm" (tmp_addr));
182 mexitcount_overhead = KCOUNT(p, PC_TO_I(p, tmp_addr));
184 p->state = GMON_PROF_OFF;
189 nullfunc_loop_profiled_time = 0;
190 for (tmp_addr = (uintfptr_t)nullfunc_loop_profiled;
191 tmp_addr < (uintfptr_t)nullfunc_loop_profiled_end;
192 tmp_addr += HISTFRACTION * sizeof(HISTCOUNTER))
193 nullfunc_loop_profiled_time += KCOUNT(p, PC_TO_I(p, tmp_addr));
194 #define CALIB_DOSCALE(count) (((count) + CALIB_SCALE / 3) / CALIB_SCALE)
195 #define c2n(count, freq) ((int)((count) * 1000000000LL / freq))
196 kprintf("cputime %d, empty_loop %d, nullfunc_loop_profiled %d, mcount %d, mexitcount %d\n",
197 CALIB_DOSCALE(c2n(cputime_overhead, p->profrate)),
198 CALIB_DOSCALE(c2n(empty_loop_time, p->profrate)),
199 CALIB_DOSCALE(c2n(nullfunc_loop_profiled_time, p->profrate)),
200 CALIB_DOSCALE(c2n(mcount_overhead, p->profrate)),
201 CALIB_DOSCALE(c2n(mexitcount_overhead, p->profrate)));
202 cputime_overhead -= empty_loop_time;
203 mcount_overhead -= empty_loop_time;
204 mexitcount_overhead -= empty_loop_time;
207 * Profiling overheads are determined by the times between the
209 * MC1: mcount() is called
210 * MC2: cputime() (called from mcount()) latches the timer
211 * MC3: mcount() completes
212 * ME1: mexitcount() is called
213 * ME2: cputime() (called from mexitcount()) latches the timer
214 * ME3: mexitcount() completes.
215 * The times between the events vary slightly depending on instruction
216 * combination and cache misses, etc. Attempt to determine the
217 * minimum times. These can be subtracted from the profiling times
218 * without much risk of reducing the profiling times below what they
219 * would be when profiling is not configured. Abbreviate:
220 * ab = minimum time between MC1 and MC3
221 * a = minumum time between MC1 and MC2
222 * b = minimum time between MC2 and MC3
223 * cd = minimum time between ME1 and ME3
224 * c = minimum time between ME1 and ME2
225 * d = minimum time between ME2 and ME3.
226 * These satisfy the relations:
227 * ab <= mcount_overhead (just measured)
229 * cd <= mexitcount_overhead (just measured)
231 * a + d <= nullfunc_loop_profiled_time (just measured)
232 * a >= 0, b >= 0, c >= 0, d >= 0.
233 * Assume that ab and cd are equal to the minimums.
235 p->cputime_overhead = CALIB_DOSCALE(cputime_overhead);
236 p->mcount_overhead = CALIB_DOSCALE(mcount_overhead - cputime_overhead);
237 p->mexitcount_overhead = CALIB_DOSCALE(mexitcount_overhead
239 nullfunc_loop_overhead = nullfunc_loop_profiled_time - empty_loop_time;
240 p->mexitcount_post_overhead = CALIB_DOSCALE((mcount_overhead
241 - nullfunc_loop_overhead)
243 p->mexitcount_pre_overhead = p->mexitcount_overhead
244 + p->cputime_overhead
245 - p->mexitcount_post_overhead;
246 p->mcount_pre_overhead = CALIB_DOSCALE(nullfunc_loop_overhead)
247 - p->mexitcount_post_overhead;
248 p->mcount_post_overhead = p->mcount_overhead
249 + p->cputime_overhead
250 - p->mcount_pre_overhead;
252 "Profiling overheads: mcount: %d+%d, %d+%d; mexitcount: %d+%d, %d+%d nsec\n",
253 c2n(p->cputime_overhead, p->profrate),
254 c2n(p->mcount_overhead, p->profrate),
255 c2n(p->mcount_pre_overhead, p->profrate),
256 c2n(p->mcount_post_overhead, p->profrate),
257 c2n(p->cputime_overhead, p->profrate),
258 c2n(p->mexitcount_overhead, p->profrate),
259 c2n(p->mexitcount_pre_overhead, p->profrate),
260 c2n(p->mexitcount_post_overhead, p->profrate));
262 "Profiling overheads: mcount: %d+%d, %d+%d; mexitcount: %d+%d, %d+%d cycles\n",
263 p->cputime_overhead, p->mcount_overhead,
264 p->mcount_pre_overhead, p->mcount_post_overhead,
265 p->cputime_overhead, p->mexitcount_overhead,
266 p->mexitcount_pre_overhead, p->mexitcount_post_overhead);
271 * Return kernel profiling information.
274 sysctl_kern_prof(SYSCTL_HANDLER_ARGS)
276 int *name = (int *) arg1;
277 u_int namelen = arg2;
278 struct gmonparam *gp = &_gmonparam;
282 /* all sysctl names at this level are terminal */
284 return (ENOTDIR); /* overloaded */
289 error = sysctl_handle_int(oidp, &state, 0, req);
294 lwkt_gettoken(&proc0.p_token);
295 if (state == GMON_PROF_OFF) {
297 stopprofclock(&proc0);
299 } else if (state == GMON_PROF_ON) {
300 gp->state = GMON_PROF_OFF;
302 gp->profrate = profhz;
303 startprofclock(&proc0);
306 } else if (state == GMON_PROF_HIRES) {
307 gp->state = GMON_PROF_OFF;
308 stopprofclock(&proc0);
312 } else if (state != gp->state) {
315 lwkt_reltoken(&proc0.p_token);
318 return (sysctl_handle_opaque(oidp,
319 gp->kcount, gp->kcountsize, req));
321 return (sysctl_handle_opaque(oidp,
322 gp->froms, gp->fromssize, req));
324 return (sysctl_handle_opaque(oidp,
325 gp->tos, gp->tossize, req));
326 case GPROF_GMONPARAM:
327 return (sysctl_handle_opaque(oidp, gp, sizeof *gp, req));
334 SYSCTL_NODE(_kern, KERN_PROF, prof, CTLFLAG_RW, sysctl_kern_prof, "");
338 * Profiling system call.
340 * The scale factor is a fixed point number with 16 bits of fraction, so that
341 * 1.0 is represented as 0x10000. A scale factor of 0 turns off profiling.
346 sys_profil(struct profil_args *uap)
348 struct proc *p = curproc;
351 if (uap->scale > (1 << 16))
353 lwkt_gettoken(&p->p_token);
354 if (uap->scale == 0) {
359 /* Block profile interrupts while changing state. */
361 upp->pr_off = uap->offset;
362 upp->pr_scale = uap->scale;
363 upp->pr_base = uap->samples;
364 upp->pr_size = uap->size;
368 lwkt_reltoken(&p->p_token);
374 * Scale is a fixed-point number with the binary point 16 bits
375 * into the value, and is <= 1.0. pc is at most 32 bits, so the
376 * intermediate result is at most 48 bits.
378 #define PC_TO_INDEX(pc, prof) \
379 ((int)(((u_quad_t)((pc) - (prof)->pr_off) * \
380 (u_quad_t)((prof)->pr_scale)) >> 16) & ~1)
383 * Collect user-level profiling statistics; called on a profiling tick,
384 * when a process is running in user-mode. This routine may be called
385 * from an interrupt context.
387 * Note that we may (rarely) not get around to the AST soon enough, and
388 * lose profile ticks when the next tick overwrites this one, but in this
389 * case the system is overloaded and the profile is probably already
393 addupc_intr(struct proc *p, u_long pc, u_int ticks)
401 if (pc < prof->pr_off ||
402 (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size)
403 return; /* out of range; ignore */
406 prof->pr_ticks = ticks;
411 * Much like before, but we can afford to take faults here. If the
412 * update fails, we simply turn off profiling.
415 addupc_task(struct proc *p, u_long pc, u_int ticks)
422 /* Testing P_PROFIL may be unnecessary, but is certainly safe. */
423 if ((p->p_flags & P_PROFIL) == 0 || ticks == 0)
427 if (pc < prof->pr_off ||
428 (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size)
431 addr = prof->pr_base + i;
432 if (copyin(addr, (caddr_t)&v, sizeof(v)) == 0) {
434 if (copyout((caddr_t)&v, addr, sizeof(v)) == 0)