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- At the top of sleepq_catch_signals() lock the thread and check TDF_NEEDSIGCHK

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before doing the very expensive cursig() and related locking.  NEEDSIGCHK
   is updated whenever our signal mask change or when a signal is delivered and
   should be sufficient to avoid the more expensive tests.  This eliminates
   another source of PROC_LOCK contention in multithreaded programs.
This commit is contained in:
Jeff Roberson 2008-03-19 07:35:14 +00:00
parent bd4e153568
commit 241fbd3d13
1 changed files with 12 additions and 4 deletions
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16
sys/kern/subr_sleepqueue.c
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@ -385,12 +385,20 @@ sleepq_catch_signals(void *wchan, int pri)
sc = SC_LOOKUP(wchan);
mtx_assert(&sc->sc_lock, MA_OWNED);
MPASS(wchan != NULL);
/*
* See if there are any pending signals for this thread. If not
* we can switch immediately. Otherwise do the signal processing
* directly.
*/
thread_lock(td);
if ((td->td_flags & TDF_NEEDSIGCHK) == 0) {
sleepq_switch(wchan, pri);
return (0);
}
thread_unlock(td);
mtx_unlock_spin(&sc->sc_lock);
CTR3(KTR_PROC, "sleepq catching signals: thread %p (pid %ld, %s)",
(void *)td, (long)p->p_pid, td->td_name);
mtx_unlock_spin(&sc->sc_lock);
/* See if there are any pending signals for this thread. */
PROC_LOCK(p);
ps = p->p_sigacts;
mtx_lock(&ps->ps_mtx);