diff options
Diffstat (limited to 'src/backend/storage/buffer/bufmgr.c')
| -rw-r--r-- | src/backend/storage/buffer/bufmgr.c | 104 |
1 files changed, 4 insertions, 100 deletions
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c index 907e8194743..8ed03138fac 100644 --- a/src/backend/storage/buffer/bufmgr.c +++ b/src/backend/storage/buffer/bufmgr.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/storage/buffer/bufmgr.c,v 1.94 2000/11/20 16:47:31 petere Exp $ + * $Header: /cvsroot/pgsql/src/backend/storage/buffer/bufmgr.c,v 1.95 2000/11/28 23:27:55 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -93,12 +93,6 @@ extern void AbortBufferIO(void); */ #define BUFFER_IS_BROKEN(buf) ((buf->flags & BM_IO_ERROR) && !(buf->flags & BM_DIRTY)) -#ifndef HAS_TEST_AND_SET -static void SignalIO(BufferDesc *buf); -extern long *NWaitIOBackendP; /* defined in buf_init.c */ - -#endif /* HAS_TEST_AND_SET */ - static Buffer ReadBufferWithBufferLock(Relation relation, BlockNumber blockNum, bool bufferLockHeld); static BufferDesc *BufferAlloc(Relation reln, BlockNumber blockNum, @@ -1187,27 +1181,7 @@ BufferSync() * * Should be entered with buffer manager spinlock held; releases it before * waiting and re-acquires it afterwards. - * - * OLD NOTES: - * Because IO_IN_PROGRESS conflicts are - * expected to be rare, there is only one BufferIO - * lock in the entire system. All processes block - * on this semaphore when they try to use a buffer - * that someone else is faulting in. Whenever a - * process finishes an IO and someone is waiting for - * the buffer, BufferIO is signaled (SignalIO). All - * waiting processes then wake up and check to see - * if their buffer is now ready. This implementation - * is simple, but efficient enough if WaitIO is - * rarely called by multiple processes simultaneously. - * - * NEW NOTES: - * The above is true only on machines without test-and-set - * semaphores (which we hope are few, these days). On better - * hardware, each buffer has a spinlock that we can wait on. */ -#ifdef HAS_TEST_AND_SET - static void WaitIO(BufferDesc *buf, SPINLOCK spinlock) { @@ -1224,43 +1198,6 @@ WaitIO(BufferDesc *buf, SPINLOCK spinlock) } } -#else /* !HAS_TEST_AND_SET */ - -IpcSemaphoreId WaitIOSemId; -IpcSemaphoreId WaitCLSemId; - -static void -WaitIO(BufferDesc *buf, SPINLOCK spinlock) -{ - bool inProgress; - - for (;;) - { - - /* wait until someone releases IO lock */ - (*NWaitIOBackendP)++; - SpinRelease(spinlock); - IpcSemaphoreLock(WaitIOSemId, 0, 1); - SpinAcquire(spinlock); - inProgress = (buf->flags & BM_IO_IN_PROGRESS); - if (!inProgress) - break; - } -} - -/* - * SignalIO - */ -static void -SignalIO(BufferDesc *buf) -{ - /* somebody better be waiting. */ - Assert(buf->refcount > 1); - IpcSemaphoreUnlock(WaitIOSemId, 0, *NWaitIOBackendP); - *NWaitIOBackendP = 0; -} - -#endif /* HAS_TEST_AND_SET */ long NDirectFileRead; /* some I/O's are direct file access. * bypass bufmgr */ @@ -2297,11 +2234,7 @@ UnlockBuffers() Assert(BufferIsValid(i + 1)); buf = &(BufferDescriptors[i]); -#ifdef HAS_TEST_AND_SET S_LOCK(&(buf->cntx_lock)); -#else - IpcSemaphoreLock(WaitCLSemId, 0, IpcExclusiveLock); -#endif if (BufferLocks[i] & BL_R_LOCK) { @@ -2324,11 +2257,9 @@ UnlockBuffers() Assert(buf->w_lock); buf->w_lock = false; } -#ifdef HAS_TEST_AND_SET + S_UNLOCK(&(buf->cntx_lock)); -#else - IpcSemaphoreUnlock(WaitCLSemId, 0, IpcExclusiveLock); -#endif + BufferLocks[i] = 0; } } @@ -2346,11 +2277,7 @@ LockBuffer(Buffer buffer, int mode) buf = &(BufferDescriptors[buffer - 1]); buflock = &(BufferLocks[buffer - 1]); -#ifdef HAS_TEST_AND_SET S_LOCK(&(buf->cntx_lock)); -#else - IpcSemaphoreLock(WaitCLSemId, 0, IpcExclusiveLock); -#endif if (mode == BUFFER_LOCK_UNLOCK) { @@ -2380,15 +2307,9 @@ LockBuffer(Buffer buffer, int mode) Assert(!(*buflock & (BL_R_LOCK | BL_W_LOCK | BL_RI_LOCK))); while (buf->ri_lock || buf->w_lock) { -#ifdef HAS_TEST_AND_SET S_UNLOCK(&(buf->cntx_lock)); s_lock_sleep(i++); S_LOCK(&(buf->cntx_lock)); -#else - IpcSemaphoreUnlock(WaitCLSemId, 0, IpcExclusiveLock); - s_lock_sleep(i++); - IpcSemaphoreLock(WaitCLSemId, 0, IpcExclusiveLock); -#endif } (buf->r_locks)++; *buflock |= BL_R_LOCK; @@ -2412,15 +2333,9 @@ LockBuffer(Buffer buffer, int mode) *buflock |= BL_RI_LOCK; buf->ri_lock = true; } -#ifdef HAS_TEST_AND_SET S_UNLOCK(&(buf->cntx_lock)); s_lock_sleep(i++); S_LOCK(&(buf->cntx_lock)); -#else - IpcSemaphoreUnlock(WaitCLSemId, 0, IpcExclusiveLock); - s_lock_sleep(i++); - IpcSemaphoreLock(WaitCLSemId, 0, IpcExclusiveLock); -#endif } buf->w_lock = true; *buflock |= BL_W_LOCK; @@ -2438,12 +2353,7 @@ LockBuffer(Buffer buffer, int mode) else elog(ERROR, "LockBuffer: unknown lock mode %d", mode); -#ifdef HAS_TEST_AND_SET S_UNLOCK(&(buf->cntx_lock)); -#else - IpcSemaphoreUnlock(WaitCLSemId, 0, IpcExclusiveLock); -#endif - } /* @@ -2471,7 +2381,6 @@ StartBufferIO(BufferDesc *buf, bool forInput) Assert(!InProgressBuf); Assert(!(buf->flags & BM_IO_IN_PROGRESS)); buf->flags |= BM_IO_IN_PROGRESS; -#ifdef HAS_TEST_AND_SET /* * There used to be @@ -2485,7 +2394,7 @@ StartBufferIO(BufferDesc *buf, bool forInput) * happen -- tgl */ S_LOCK(&(buf->io_in_progress_lock)); -#endif /* HAS_TEST_AND_SET */ + InProgressBuf = buf; IsForInput = forInput; } @@ -2502,12 +2411,7 @@ static void TerminateBufferIO(BufferDesc *buf) { Assert(buf == InProgressBuf); -#ifdef HAS_TEST_AND_SET S_UNLOCK(&(buf->io_in_progress_lock)); -#else - if (buf->refcount > 1) - SignalIO(buf); -#endif /* HAS_TEST_AND_SET */ InProgressBuf = (BufferDesc *) 0; } |