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Take spin count into account in RtlEnterCriticalSection.

This commit is contained in:
Alexandre Julliard 2004-06-17 23:11:08 +00:00
parent 2bcef9e1fb
commit 2ed053b5a0
1 changed files with 26 additions and 0 deletions
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26
dlls/ntdll/critsection.c
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@ -46,6 +46,15 @@ inline static LONG interlocked_dec( PLONG dest )
return interlocked_xchg_add( dest, -1 ) - 1;
}
inline static void small_pause(void)
{
#ifdef __i386__
__asm__ __volatile__( "rep;nop" : : : "memory" );
#else
__asm__ __volatile__( "" : : : "memory" );
#endif
}
/***********************************************************************
* get_semaphore
*/
@ -261,6 +270,22 @@ NTSTATUS WINAPI RtlpUnWaitCriticalSection( RTL_CRITICAL_SECTION *crit )
*/
NTSTATUS WINAPI RtlEnterCriticalSection( RTL_CRITICAL_SECTION *crit )
{
if (crit->SpinCount)
{
ULONG count;
if (RtlTryEnterCriticalSection( crit )) return STATUS_SUCCESS;
for (count = crit->SpinCount; count > 0; count--)
{
if (crit->LockCount > 0) break; /* more than one waiter, don't bother spinning */
if (crit->LockCount == -1) /* try again */
{
if (interlocked_cmpxchg( &crit->LockCount, 0, -1 ) == -1) goto done;
}
small_pause();
}
}
if (interlocked_inc( &crit->LockCount ))
{
if (crit->OwningThread == (HANDLE)GetCurrentThreadId())
@ -272,6 +297,7 @@ NTSTATUS WINAPI RtlEnterCriticalSection( RTL_CRITICAL_SECTION *crit )
/* Now wait for it */
RtlpWaitForCriticalSection( crit );
}
done:
crit->OwningThread = (HANDLE)GetCurrentThreadId();
crit->RecursionCount = 1;
return STATUS_SUCCESS;