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Fix some nits in lock profiling for rwlocks:

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- Properly note when a read lock is released.
- Always note when we contest on a read lock.
- Only note success of obtaining read locks for the first reader to match
  the behavior of sx(9).

Reviewed by:	kmacy
This commit is contained in:
John Baldwin 2007-03-07 20:48:48 +00:00
parent 224a2f3144
commit ddb38a1f3d
1 changed files with 9 additions and 6 deletions
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15
sys/kern/kern_rwlock.c
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@ -150,7 +150,7 @@ _rw_rlock(struct rwlock *rw, const char *file, int line)
#ifdef SMP
volatile struct thread *owner;
#endif
uint64_t waitstart = 0;
uint64_t waittime = 0;
int contested = 0;
uintptr_t x;
@ -192,18 +192,22 @@ _rw_rlock(struct rwlock *rw, const char *file, int line)
MPASS((x & RW_LOCK_READ_WAITERS) == 0);
if (atomic_cmpset_acq_ptr(&rw->rw_lock, x,
x + RW_ONE_READER)) {
lock_profile_obtain_lock_success(&rw->rw_object, contested, waitstart, file, line);
if (LOCK_LOG_TEST(&rw->rw_object, 0))
CTR4(KTR_LOCK,
"%s: %p succeed %p -> %p", __func__,
rw, (void *)x,
(void *)(x + RW_ONE_READER));
if (RW_READERS(x) == 0)
lock_profile_obtain_lock_success(
&rw->rw_object, contested, waittime,
file, line);
break;
}
lock_profile_obtain_lock_failed(&rw->rw_object, &contested, &waitstart);
cpu_spinwait();
continue;
}
lock_profile_obtain_lock_failed(&rw->rw_object, &contested,
&waittime);
/*
* Okay, now it's the hard case. Some other thread already
@ -250,7 +254,6 @@ _rw_rlock(struct rwlock *rw, const char *file, int line)
*/
owner = (struct thread *)RW_OWNER(x);
if (TD_IS_RUNNING(owner)) {
lock_profile_obtain_lock_failed(&rw->rw_object, &contested, &waitstart);
turnstile_release(&rw->rw_object);
if (LOCK_LOG_TEST(&rw->rw_object, 0))
CTR3(KTR_LOCK, "%s: spinning on %p held by %p",
@ -316,8 +319,7 @@ _rw_runlock(struct rwlock *rw, const char *file, int line)
break;
}
continue;
} else
lock_profile_release_lock(&rw->rw_object);
}
/*
@ -401,6 +403,7 @@ _rw_runlock(struct rwlock *rw, const char *file, int line)
turnstile_unpend(ts, TS_SHARED_LOCK);
break;
}
lock_profile_release_lock(&rw->rw_object);
}
/*