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Changed sAreaCacheLock from mutex to rw_lock. This reduces the lock's

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contention about two orders of magnitude. Most of it seems to be taken over
by other locks, though. Yields only small improvements for the -j8 Haiku
image build.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@34937 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Ingo Weinhold
2010-01-07 15:36:18 +00:00
parent 77690f288e
commit bd0bff449f
1 changed files with 8 additions and 8 deletions
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src/system/kernel/vm/vm.cpp
+8 -8
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@@ -104,7 +104,7 @@ public:
static mutex sMappingLock = MUTEX_INITIALIZER("page mappings"); static mutex sMappingLock = MUTEX_INITIALIZER("page mappings");
static mutex sAreaCacheLock = MUTEX_INITIALIZER("area->cache"); static rw_lock sAreaCacheLock = RW_LOCK_INITIALIZER("area->cache");
static off_t sAvailableMemory; static off_t sAvailableMemory;
static off_t sNeededMemory; static off_t sNeededMemory;
@@ -1413,22 +1413,22 @@ vm_map_file(team_id aid, const char* name, void** address, uint32 addressSpec,
VMCache* VMCache*
vm_area_get_locked_cache(VMArea* area) vm_area_get_locked_cache(VMArea* area)
{ {
mutex_lock(&sAreaCacheLock); rw_lock_read_lock(&sAreaCacheLock);
while (true) { while (true) {
VMCache* cache = area->cache; VMCache* cache = area->cache;
if (!cache->SwitchLock(&sAreaCacheLock)) { if (!cache->SwitchFromReadLock(&sAreaCacheLock)) {
// cache has been deleted // cache has been deleted
mutex_lock(&sAreaCacheLock); rw_lock_read_lock(&sAreaCacheLock);
continue; continue;
} }
mutex_lock(&sAreaCacheLock); rw_lock_read_lock(&sAreaCacheLock);
if (cache == area->cache) { if (cache == area->cache) {
cache->AcquireRefLocked(); cache->AcquireRefLocked();
mutex_unlock(&sAreaCacheLock); rw_lock_read_unlock(&sAreaCacheLock);
return cache; return cache;
} }
@@ -1665,9 +1665,9 @@ vm_copy_on_write_area(VMCache* lowerCache)
upperCache->virtual_end = lowerCache->virtual_end; upperCache->virtual_end = lowerCache->virtual_end;
// transfer the lower cache areas to the upper cache // transfer the lower cache areas to the upper cache
mutex_lock(&sAreaCacheLock); rw_lock_write_lock(&sAreaCacheLock);
upperCache->TransferAreas(lowerCache); upperCache->TransferAreas(lowerCache);
mutex_unlock(&sAreaCacheLock); rw_lock_write_unlock(&sAreaCacheLock);
lowerCache->AddConsumer(upperCache); lowerCache->AddConsumer(upperCache);