2 * Copyright (c) 2009, 2010 The DragonFly Project. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
5 * by Alex Hornung <ahornung@gmail.com>
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
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
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
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.
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,
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31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 #include <sys/param.h>
35 #include <sys/systm.h>
36 #include <sys/kernel.h>
38 #include <sys/sysctl.h>
41 #include <sys/diskslice.h>
43 #include <machine/atomic.h>
44 #include <sys/thread.h>
45 #include <sys/thread2.h>
46 #include <sys/ctype.h>
48 #include <sys/syslog.h>
49 #include <sys/dsched.h>
50 #include <machine/param.h>
52 #include <kern/dsched/fq/fq.h>
54 static int dsched_fq_version_maj = 1;
55 static int dsched_fq_version_min = 0;
57 /* Make sure our structs fit */
58 CTASSERT(sizeof(struct fq_thread_io) <= DSCHED_THREAD_IO_MAX_SZ);
59 CTASSERT(sizeof(struct fq_disk_ctx) <= DSCHED_DISK_CTX_MAX_SZ);
61 struct dsched_fq_stats fq_stats;
63 extern struct dsched_policy dsched_fq_policy;
66 fq_dispatcher(struct fq_disk_ctx *diskctx)
68 struct dsched_thread_io *ds_tdio, *ds_tdio2;
69 struct fq_thread_io *tdio;
70 struct bio *bio, *bio2;
74 * We need to manually assign an tdio to the tdctx of this thread
75 * since it isn't assigned one during fq_prepare, as the disk
78 tdio = (struct fq_thread_io *)dsched_new_policy_thread_tdio(&diskctx->head,
81 DSCHED_DISK_CTX_LOCK(&diskctx->head);
85 if ((lksleep(diskctx, &diskctx->head.lock, 0, "fq_dispatcher", hz/15) == 0)) {
87 * We've been woken up; this either means that we are
88 * supposed to die away nicely or that the disk is idle.
91 if (__predict_false(diskctx->die == 1)) {
92 /* If we are supposed to die, drain all queues */
93 fq_drain(diskctx, FQ_DRAIN_FLUSH);
95 /* Now we can safely unlock and exit */
96 DSCHED_DISK_CTX_UNLOCK(&diskctx->head);
97 kprintf("fq_dispatcher is peacefully dying\n");
103 * We have been awakened because the disk is idle.
104 * So let's get ready to dispatch some extra bios.
109 /* Maybe the disk is idle and we just didn't get the wakeup */
111 idle = diskctx->idle;
114 * XXX: further room for improvements here. It would be better
115 * to dispatch a few requests from each tdio as to ensure
118 TAILQ_FOREACH_MUTABLE(ds_tdio, &diskctx->head.tdio_list, dlink, ds_tdio2) {
119 tdio = (struct fq_thread_io *)ds_tdio;
120 if (tdio->head.qlength == 0)
123 DSCHED_THREAD_IO_LOCK(&tdio->head);
124 if (atomic_cmpset_int(&tdio->rebalance, 1, 0))
125 fq_balance_self(tdio);
127 * XXX: why 5 extra? should probably be dynamic,
128 * relying on information on latency.
130 if ((tdio->max_tp > 0) && idle &&
131 (tdio->issued >= tdio->max_tp)) {
135 TAILQ_FOREACH_MUTABLE(bio, &tdio->head.queue, link, bio2) {
136 if (atomic_cmpset_int(&tdio->rebalance, 1, 0))
137 fq_balance_self(tdio);
138 if ((tdio->max_tp > 0) &&
139 ((tdio->issued >= tdio->max_tp)))
142 TAILQ_REMOVE(&tdio->head.queue, bio, link);
143 --tdio->head.qlength;
146 * beware that we do have an tdio reference
149 fq_dispatch(diskctx, bio, tdio);
151 DSCHED_THREAD_IO_UNLOCK(&tdio->head);
158 fq_balance_thread(struct fq_disk_ctx *diskctx)
160 struct dsched_thread_io *ds_tdio;
161 struct fq_thread_io *tdio;
162 struct timeval tv, old_tv;
163 int64_t total_budget, product;
164 int64_t budget[FQ_PRIO_MAX+1];
165 int n, i, sum, total_disk_time;
168 DSCHED_DISK_CTX_LOCK(&diskctx->head);
170 getmicrotime(&diskctx->start_interval);
174 if ((lksleep(curthread, &diskctx->head.lock, 0, "fq_balancer", hz/2) == 0)) {
175 if (__predict_false(diskctx->die)) {
176 DSCHED_DISK_CTX_UNLOCK(&diskctx->head);
181 bzero(budget, sizeof(budget));
185 old_tv = diskctx->start_interval;
188 total_disk_time = (int)(1000000*((tv.tv_sec - old_tv.tv_sec)) +
189 (tv.tv_usec - old_tv.tv_usec));
191 if (total_disk_time == 0)
194 dsched_debug(LOG_INFO, "total_disk_time = %d\n", total_disk_time);
196 diskctx->start_interval = tv;
198 diskctx->disk_busy = (100*(total_disk_time - diskctx->idle_time)) / total_disk_time;
199 if (diskctx->disk_busy < 0)
200 diskctx->disk_busy = 0;
202 diskctx->idle_time = 0;
205 TAILQ_FOREACH(ds_tdio, &diskctx->head.tdio_list, dlink) {
206 tdio = (struct fq_thread_io *)ds_tdio;
207 tdio->interval_avg_latency = tdio->avg_latency;
208 tdio->interval_transactions = tdio->transactions;
209 if (tdio->interval_transactions > 0) {
210 product = (int64_t)tdio->interval_avg_latency *
211 tdio->interval_transactions;
212 product >>= lost_bits;
213 while(total_budget >= INT64_MAX - product) {
218 total_budget += product;
219 ++budget[(tdio->head.p) ? tdio->head.p->p_ionice : 0];
220 KKASSERT(total_budget >= 0);
221 dsched_debug(LOG_INFO,
222 "%d) avg_latency = %d, transactions = %d, ioprio = %d\n",
223 n, tdio->interval_avg_latency, tdio->interval_transactions,
224 (tdio->head.p) ? tdio->head.p->p_ionice : 0);
230 tdio->transactions = 0;
231 tdio->avg_latency = 0;
235 dsched_debug(LOG_INFO, "%d procs competing for disk\n"
236 "total_budget = %jd (lost bits = %d)\n"
237 "incomplete tp = %d\n", n, (intmax_t)total_budget,
238 lost_bits, diskctx->incomplete_tp);
245 for (i = 0; i < FQ_PRIO_MAX+1; i++) {
248 sum += (FQ_PRIO_BIAS+i)*budget[i];
254 dsched_debug(LOG_INFO, "sum = %d\n", sum);
256 for (i = 0; i < FQ_PRIO_MAX+1; i++) {
261 * XXX: if we still overflow here, we really need to switch to
262 * some more advanced mechanism such as compound int128 or
263 * storing the lost bits so they can be used in the
266 diskctx->budgetpb[i] = ((FQ_PRIO_BIAS+i)*total_budget/sum) << lost_bits;
267 KKASSERT(diskctx->budgetpb[i] >= 0);
270 dsched_debug(4, "disk is %d%% busy\n", diskctx->disk_busy);
271 TAILQ_FOREACH(ds_tdio, &diskctx->head.tdio_list, dlink) {
272 tdio = (struct fq_thread_io *)ds_tdio;
276 diskctx->prev_full = diskctx->last_full;
277 diskctx->last_full = (diskctx->disk_busy >= 90)?1:0;
283 * fq_balance_self should be called from all sorts of dispatchers. It basically
284 * offloads some of the heavier calculations on throttling onto the process that
285 * wants to do I/O instead of doing it in the fq_balance thread.
286 * - should be called with diskctx lock held
289 fq_balance_self(struct fq_thread_io *tdio) {
290 struct fq_disk_ctx *diskctx;
292 int64_t budget, used_budget;
294 int64_t transactions;
296 transactions = (int64_t)tdio->interval_transactions;
297 avg_latency = (int64_t)tdio->interval_avg_latency;
298 diskctx = (struct fq_disk_ctx *)tdio->head.diskctx;
301 /* XXX: do we really require the lock? */
302 DSCHED_DISK_CTX_LOCK_ASSERT(diskctx);
305 used_budget = ((int64_t)avg_latency * transactions);
306 budget = diskctx->budgetpb[(tdio->head.p) ? tdio->head.p->p_ionice : 0];
308 if (used_budget > 0) {
309 dsched_debug(LOG_INFO,
310 "info: used_budget = %jd, budget = %jd\n",
311 (intmax_t)used_budget, budget);
314 if ((used_budget > budget) && (diskctx->disk_busy >= 90)) {
315 KKASSERT(avg_latency != 0);
317 tdio->max_tp = budget/(avg_latency);
318 atomic_add_int(&fq_stats.procs_limited, 1);
320 dsched_debug(LOG_INFO,
321 "rate limited to %d transactions\n", tdio->max_tp);
323 } else if (((used_budget*2 < budget) || (diskctx->disk_busy < 80)) &&
324 (!diskctx->prev_full && !diskctx->last_full)) {
331 do_fqstats(SYSCTL_HANDLER_ARGS)
333 return (sysctl_handle_opaque(oidp, &fq_stats, sizeof(struct dsched_fq_stats), req));
337 fq_mod_handler(module_t mod, int type, void *unused)
339 static struct sysctl_ctx_list sysctl_ctx;
340 static struct sysctl_oid *oid;
341 static char version[16];
344 ksnprintf(version, sizeof(version), "%d.%d",
345 dsched_fq_version_maj, dsched_fq_version_min);
349 bzero(&fq_stats, sizeof(struct dsched_fq_stats));
350 if ((error = dsched_register(&dsched_fq_policy)))
353 sysctl_ctx_init(&sysctl_ctx);
354 oid = SYSCTL_ADD_NODE(&sysctl_ctx,
355 SYSCTL_STATIC_CHILDREN(_dsched),
360 SYSCTL_ADD_PROC(&sysctl_ctx, SYSCTL_CHILDREN(oid),
361 OID_AUTO, "stats", CTLTYPE_OPAQUE|CTLFLAG_RD,
362 0, 0, do_fqstats, "S,dsched_fq_stats", "fq statistics");
364 SYSCTL_ADD_STRING(&sysctl_ctx, SYSCTL_CHILDREN(oid),
365 OID_AUTO, "version", CTLFLAG_RD, version, 0, "fq version");
367 kprintf("FQ scheduler policy version %d.%d loaded\n",
368 dsched_fq_version_maj, dsched_fq_version_min);
372 if ((error = dsched_unregister(&dsched_fq_policy)))
374 sysctl_ctx_free(&sysctl_ctx);
375 kprintf("FQ scheduler policy unloaded\n");
385 DSCHED_POLICY_MODULE(dsched_fq, fq_mod_handler);