- Add a facility similar to LOCK_PROFILING under SLEEPQUEUE_PROFILING. Keep
a simple (wmesg, count) tuple in a hash to keep track of how many times we sleep at each wait message. We hash on message and not channel. No line number information is given as typically wait messages are not used in more than one place. Identical strings defined at different addresses will show up with seperate counters. - Use debug.sleepq.enable to enable, .reset to reset, and .stats dumps stats. - Do an unsynchronized check in sleepq_switch() prior to switching before calling sleepq_profile() which uses a global lock to synchronize the hash. Only sleeps which actually cause a context switch are counted.
This commit is contained in:
jeff
parent
4cd4553bb5
commit
ea2b75bd30
@ -73,6 +73,7 @@ __FBSDID("$FreeBSD$");
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#include <sys/ktr.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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#include <sys/sbuf.h>
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#include <sys/sched.h>
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#include <sys/signalvar.h>
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#include <sys/sleepqueue.h>
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@ -142,6 +143,9 @@ SYSCTL_NODE(_debug_sleepq, OID_AUTO, chains, CTLFLAG_RD, 0,
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"sleepq chain stats");
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SYSCTL_UINT(_debug_sleepq, OID_AUTO, max_depth, CTLFLAG_RD, &sleepq_max_depth,
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0, "maxmimum depth achieved of a single chain");
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static void sleepq_profile(const char *wmesg);
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static int prof_enabled;
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#endif
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static struct sleepqueue_chain sleepq_chains[SC_TABLESIZE];
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static uma_zone_t sleepq_zone;
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@ -466,7 +470,10 @@ sleepq_switch(void *wchan, int pri)
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mtx_unlock_spin(&sc->sc_lock);
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return;
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}
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#ifdef SLEEPQUEUE_PROFILING
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if (prof_enabled)
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sleepq_profile(td->td_wmesg);
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#endif
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MPASS(td->td_sleepqueue == NULL);
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sched_sleep(td, pri);
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thread_lock_set(td, &sc->sc_lock);
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@ -910,6 +917,157 @@ sleepq_abort(struct thread *td, int intrval)
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sleepq_resume_thread(sq, td, 0);
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}
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#ifdef SLEEPQUEUE_PROFILING
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#define SLEEPQ_PROF_LOCATIONS 1024
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#define SLEEPQ_SBUFSIZE (40 * 512)
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struct sleepq_prof {
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LIST_ENTRY(sleepq_prof) sp_link;
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const char *sp_wmesg;
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long sp_count;
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};
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LIST_HEAD(sqphead, sleepq_prof);
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struct sqphead sleepq_prof_free;
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struct sqphead sleepq_hash[SC_TABLESIZE];
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static struct sleepq_prof sleepq_profent[SLEEPQ_PROF_LOCATIONS];
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static struct mtx sleepq_prof_lock;
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MTX_SYSINIT(sleepq_prof_lock, &sleepq_prof_lock, "sleepq_prof", MTX_SPIN);
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static void
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sleepq_profile(const char *wmesg)
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{
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struct sleepq_prof *sp;
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mtx_lock_spin(&sleepq_prof_lock);
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if (prof_enabled == 0)
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goto unlock;
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LIST_FOREACH(sp, &sleepq_hash[SC_HASH(wmesg)], sp_link)
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if (sp->sp_wmesg == wmesg)
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goto done;
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sp = LIST_FIRST(&sleepq_prof_free);
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if (sp == NULL)
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goto unlock;
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sp->sp_wmesg = wmesg;
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LIST_REMOVE(sp, sp_link);
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LIST_INSERT_HEAD(&sleepq_hash[SC_HASH(wmesg)], sp, sp_link);
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done:
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sp->sp_count++;
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unlock:
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mtx_unlock_spin(&sleepq_prof_lock);
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return;
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}
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static void
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sleepq_prof_reset(void)
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{
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struct sleepq_prof *sp;
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int enabled;
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int i;
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mtx_lock_spin(&sleepq_prof_lock);
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enabled = prof_enabled;
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prof_enabled = 0;
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for (i = 0; i < SC_TABLESIZE; i++)
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LIST_INIT(&sleepq_hash[i]);
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LIST_INIT(&sleepq_prof_free);
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for (i = 0; i < SLEEPQ_PROF_LOCATIONS; i++) {
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sp = &sleepq_profent[i];
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sp->sp_wmesg = NULL;
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sp->sp_count = 0;
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LIST_INSERT_HEAD(&sleepq_prof_free, sp, sp_link);
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}
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prof_enabled = enabled;
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mtx_unlock_spin(&sleepq_prof_lock);
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}
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static int
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enable_sleepq_prof(SYSCTL_HANDLER_ARGS)
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{
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int error, v;
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v = prof_enabled;
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error = sysctl_handle_int(oidp, &v, v, req);
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if (error)
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return (error);
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if (req->newptr == NULL)
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return (error);
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if (v == prof_enabled)
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return (0);
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if (v == 1)
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sleepq_prof_reset();
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mtx_lock_spin(&sleepq_prof_lock);
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prof_enabled = !!v;
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mtx_unlock_spin(&sleepq_prof_lock);
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return (0);
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}
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static int
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reset_sleepq_prof_stats(SYSCTL_HANDLER_ARGS)
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{
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int error, v;
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v = 0;
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error = sysctl_handle_int(oidp, &v, 0, req);
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if (error)
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return (error);
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if (req->newptr == NULL)
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return (error);
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if (v == 0)
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return (0);
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sleepq_prof_reset();
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return (0);
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}
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static int
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dump_sleepq_prof_stats(SYSCTL_HANDLER_ARGS)
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{
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static int multiplier = 1;
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struct sleepq_prof *sp;
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struct sbuf *sb;
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int enabled;
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int error;
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int i;
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retry_sbufops:
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sb = sbuf_new(NULL, NULL, SLEEPQ_SBUFSIZE * multiplier, SBUF_FIXEDLEN);
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sbuf_printf(sb, "\nwmesg\tcount\n");
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enabled = prof_enabled;
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mtx_lock_spin(&sleepq_prof_lock);
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prof_enabled = 0;
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mtx_unlock_spin(&sleepq_prof_lock);
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for (i = 0; i < SC_TABLESIZE; i++) {
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LIST_FOREACH(sp, &sleepq_hash[i], sp_link) {
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sbuf_printf(sb, "%s\t%ld\n",
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sp->sp_wmesg, sp->sp_count);
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if (sbuf_overflowed(sb)) {
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sbuf_delete(sb);
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multiplier++;
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goto retry_sbufops;
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}
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}
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}
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mtx_lock_spin(&sleepq_prof_lock);
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prof_enabled = enabled;
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mtx_unlock_spin(&sleepq_prof_lock);
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sbuf_finish(sb);
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error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1);
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sbuf_delete(sb);
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return (error);
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}
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SYSCTL_PROC(_debug_sleepq, OID_AUTO, stats, CTLTYPE_STRING | CTLFLAG_RD,
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NULL, 0, dump_sleepq_prof_stats, "A", "Sleepqueue profiling statistics");
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SYSCTL_PROC(_debug_sleepq, OID_AUTO, reset, CTLTYPE_INT | CTLFLAG_RW,
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NULL, 0, reset_sleepq_prof_stats, "I",
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"Reset sleepqueue profiling statistics");
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SYSCTL_PROC(_debug_sleepq, OID_AUTO, enable, CTLTYPE_INT | CTLFLAG_RW,
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NULL, 0, enable_sleepq_prof, "I", "Enable sleepqueue profiling");
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#endif
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#ifdef DDB
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DB_SHOW_COMMAND(sleepq, db_show_sleepqueue)
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{
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