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Add appropriate IA32 "pause" instructions to improve performanec on

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Pentium 4's and newer IA32 processors.  The "pause" instruction has been
verified by Intel to be a NOP on all currently existing IA32 processors
prior to the Pentium 4.
This commit is contained in:
jhb 2002-05-21 22:26:35 +00:00
parent 8f86bf993e
commit 3b7890a56f
2 changed files with 34 additions and 2 deletions
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18
sys/kern/kern_mutex.c
View File

@ -488,6 +488,9 @@ _mtx_lock_sleep(struct mtx *m, int opts, const char *file, int line)
*/
if ((v = m->mtx_lock) == MTX_UNOWNED) {
mtx_unlock_spin(&sched_lock);
#ifdef __i386__
cpu_pause();
#endif
continue;
}
@ -515,6 +518,9 @@ _mtx_lock_sleep(struct mtx *m, int opts, const char *file, int line)
!atomic_cmpset_ptr(&m->mtx_lock, (void *)v,
(void *)(v | MTX_CONTESTED))) {
mtx_unlock_spin(&sched_lock);
#ifdef __i386__
cpu_pause();
#endif
continue;
}
@ -527,6 +533,9 @@ _mtx_lock_sleep(struct mtx *m, int opts, const char *file, int line)
if (m != &Giant && owner->td_kse != NULL &&
owner->td_kse->ke_oncpu != NOCPU) {
mtx_unlock_spin(&sched_lock);
#ifdef __i386__
cpu_pause();
#endif
continue;
}
#endif /* SMP && ADAPTIVE_MUTEXES */
@ -619,8 +628,12 @@ _mtx_lock_spin(struct mtx *m, int opts, const char *file, int line)
/* Give interrupts a chance while we spin. */
critical_exit();
while (m->mtx_lock != MTX_UNOWNED) {
if (i++ < 10000000)
if (i++ < 10000000) {
#ifdef __i386__
cpu_pause();
#endif
continue;
}
if (i < 60000000)
DELAY(1);
#ifdef DDB
@ -630,6 +643,9 @@ _mtx_lock_spin(struct mtx *m, int opts, const char *file, int line)
#endif
panic("spin lock %s held by %p for > 5 seconds",
m->mtx_object.lo_name, (void *)m->mtx_lock);
#ifdef __i386__
cpu_pause();
#endif
}
critical_enter();
}

18
sys/kern/subr_turnstile.c
View File

@ -488,6 +488,9 @@ _mtx_lock_sleep(struct mtx *m, int opts, const char *file, int line)
*/
if ((v = m->mtx_lock) == MTX_UNOWNED) {
mtx_unlock_spin(&sched_lock);
#ifdef __i386__
cpu_pause();
#endif
continue;
}
@ -515,6 +518,9 @@ _mtx_lock_sleep(struct mtx *m, int opts, const char *file, int line)
!atomic_cmpset_ptr(&m->mtx_lock, (void *)v,
(void *)(v | MTX_CONTESTED))) {
mtx_unlock_spin(&sched_lock);
#ifdef __i386__
cpu_pause();
#endif
continue;
}
@ -527,6 +533,9 @@ _mtx_lock_sleep(struct mtx *m, int opts, const char *file, int line)
if (m != &Giant && owner->td_kse != NULL &&
owner->td_kse->ke_oncpu != NOCPU) {
mtx_unlock_spin(&sched_lock);
#ifdef __i386__
cpu_pause();
#endif
continue;
}
#endif /* SMP && ADAPTIVE_MUTEXES */
@ -619,8 +628,12 @@ _mtx_lock_spin(struct mtx *m, int opts, const char *file, int line)
/* Give interrupts a chance while we spin. */
critical_exit();
while (m->mtx_lock != MTX_UNOWNED) {
if (i++ < 10000000)
if (i++ < 10000000) {
#ifdef __i386__
cpu_pause();
#endif
continue;
}
if (i < 60000000)
DELAY(1);
#ifdef DDB
@ -630,6 +643,9 @@ _mtx_lock_spin(struct mtx *m, int opts, const char *file, int line)
#endif
panic("spin lock %s held by %p for > 5 seconds",
m->mtx_object.lo_name, (void *)m->mtx_lock);
#ifdef __i386__
cpu_pause();
#endif
}
critical_enter();
}