diff options
Diffstat (limited to 'src/backend/storage')
| -rw-r--r-- | src/backend/storage/ipc/ipci.c | 10 | ||||
| -rw-r--r-- | src/backend/storage/lmgr/Makefile | 1 | ||||
| -rw-r--r-- | src/backend/storage/lmgr/meson.build | 1 | ||||
| -rw-r--r-- | src/backend/storage/lmgr/s_lock.c | 2 | ||||
| -rw-r--r-- | src/backend/storage/lmgr/spin.c | 180 |
5 files changed, 1 insertions, 193 deletions
diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c index b6c3b169509..34e4d17b67d 100644 --- a/src/backend/storage/ipc/ipci.c +++ b/src/backend/storage/ipc/ipci.c @@ -94,7 +94,6 @@ CalculateShmemSize(int *num_semaphores) /* Compute number of semaphores we'll need */ numSemas = ProcGlobalSemas(); - numSemas += SpinlockSemas(); /* Return the number of semaphores if requested by the caller */ if (num_semaphores) @@ -111,7 +110,6 @@ CalculateShmemSize(int *num_semaphores) */ size = 100000; size = add_size(size, PGSemaphoreShmemSize(numSemas)); - size = add_size(size, SpinlockSemaSize()); size = add_size(size, hash_estimate_size(SHMEM_INDEX_SIZE, sizeof(ShmemIndexEnt))); size = add_size(size, dsm_estimate_size()); @@ -226,14 +224,6 @@ CreateSharedMemoryAndSemaphores(void) PGReserveSemaphores(numSemas); /* - * If spinlocks are disabled, initialize emulation layer (which depends on - * semaphores, so the order is important here). - */ -#ifndef HAVE_SPINLOCKS - SpinlockSemaInit(); -#endif - - /* * Set up shared memory allocation mechanism */ InitShmemAllocation(); diff --git a/src/backend/storage/lmgr/Makefile b/src/backend/storage/lmgr/Makefile index 3f89548bde6..6cbaf23b855 100644 --- a/src/backend/storage/lmgr/Makefile +++ b/src/backend/storage/lmgr/Makefile @@ -21,7 +21,6 @@ OBJS = \ predicate.o \ proc.o \ s_lock.o \ - spin.o include $(top_srcdir)/src/backend/common.mk diff --git a/src/backend/storage/lmgr/meson.build b/src/backend/storage/lmgr/meson.build index 05ac41e809a..d43511925e1 100644 --- a/src/backend/storage/lmgr/meson.build +++ b/src/backend/storage/lmgr/meson.build @@ -9,5 +9,4 @@ backend_sources += files( 'predicate.c', 'proc.c', 's_lock.c', - 'spin.c', ) diff --git a/src/backend/storage/lmgr/s_lock.c b/src/backend/storage/lmgr/s_lock.c index cba48b3e778..69549a65dba 100644 --- a/src/backend/storage/lmgr/s_lock.c +++ b/src/backend/storage/lmgr/s_lock.c @@ -1,7 +1,7 @@ /*------------------------------------------------------------------------- * * s_lock.c - * Hardware-dependent implementation of spinlocks. + * Implementation of spinlocks. * * When waiting for a contended spinlock we loop tightly for awhile, then * delay using pg_usleep() and try again. Preferably, "awhile" should be a diff --git a/src/backend/storage/lmgr/spin.c b/src/backend/storage/lmgr/spin.c deleted file mode 100644 index 50cb99cd3b6..00000000000 --- a/src/backend/storage/lmgr/spin.c +++ /dev/null @@ -1,180 +0,0 @@ -/*------------------------------------------------------------------------- - * - * spin.c - * Hardware-independent implementation of spinlocks. - * - * - * For machines that have test-and-set (TAS) instructions, s_lock.h/.c - * define the spinlock implementation. This file contains only a stub - * implementation for spinlocks using PGSemaphores. Unless semaphores - * are implemented in a way that doesn't involve a kernel call, this - * is too slow to be very useful :-( - * - * - * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group - * Portions Copyright (c) 1994, Regents of the University of California - * - * - * IDENTIFICATION - * src/backend/storage/lmgr/spin.c - * - *------------------------------------------------------------------------- - */ -#include "postgres.h" - -#include "storage/pg_sema.h" -#include "storage/shmem.h" -#include "storage/spin.h" - - -#ifndef HAVE_SPINLOCKS - -/* - * No TAS, so spinlocks are implemented as PGSemaphores. - */ - -#ifndef HAVE_ATOMICS -#define NUM_EMULATION_SEMAPHORES (NUM_SPINLOCK_SEMAPHORES + NUM_ATOMICS_SEMAPHORES) -#else -#define NUM_EMULATION_SEMAPHORES (NUM_SPINLOCK_SEMAPHORES) -#endif /* HAVE_ATOMICS */ - -PGSemaphore *SpinlockSemaArray; - -#else /* !HAVE_SPINLOCKS */ - -#define NUM_EMULATION_SEMAPHORES 0 - -#endif /* HAVE_SPINLOCKS */ - -/* - * Report the amount of shared memory needed to store semaphores for spinlock - * support. - */ -Size -SpinlockSemaSize(void) -{ - return NUM_EMULATION_SEMAPHORES * sizeof(PGSemaphore); -} - -/* - * Report number of semaphores needed to support spinlocks. - */ -int -SpinlockSemas(void) -{ - return NUM_EMULATION_SEMAPHORES; -} - -#ifndef HAVE_SPINLOCKS - -/* - * Initialize spinlock emulation. - * - * This must be called after PGReserveSemaphores(). - */ -void -SpinlockSemaInit(void) -{ - PGSemaphore *spinsemas; - int nsemas = SpinlockSemas(); - int i; - - /* - * We must use ShmemAllocUnlocked(), since the spinlock protecting - * ShmemAlloc() obviously can't be ready yet. - */ - spinsemas = (PGSemaphore *) ShmemAllocUnlocked(SpinlockSemaSize()); - for (i = 0; i < nsemas; ++i) - spinsemas[i] = PGSemaphoreCreate(); - SpinlockSemaArray = spinsemas; -} - -/* - * s_lock.h hardware-spinlock emulation using semaphores - * - * We map all spinlocks onto NUM_EMULATION_SEMAPHORES semaphores. It's okay to - * map multiple spinlocks onto one semaphore because no process should ever - * hold more than one at a time. We just need enough semaphores so that we - * aren't adding too much extra contention from that. - * - * There is one exception to the restriction of only holding one spinlock at a - * time, which is that it's ok if emulated atomic operations are nested inside - * spinlocks. To avoid the danger of spinlocks and atomic using the same sema, - * we make sure "normal" spinlocks and atomics backed by spinlocks use - * distinct semaphores (see the nested argument to s_init_lock_sema). - * - * slock_t is just an int for this implementation; it holds the spinlock - * number from 1..NUM_EMULATION_SEMAPHORES. We intentionally ensure that 0 - * is not a valid value, so that testing with this code can help find - * failures to initialize spinlocks. - */ - -static inline void -s_check_valid(int lockndx) -{ - if (unlikely(lockndx <= 0 || lockndx > NUM_EMULATION_SEMAPHORES)) - elog(ERROR, "invalid spinlock number: %d", lockndx); -} - -void -s_init_lock_sema(volatile slock_t *lock, bool nested) -{ - static uint32 counter = 0; - uint32 offset; - uint32 sema_total; - uint32 idx; - - if (nested) - { - /* - * To allow nesting atomics inside spinlocked sections, use a - * different spinlock. See comment above. - */ - offset = 1 + NUM_SPINLOCK_SEMAPHORES; - sema_total = NUM_ATOMICS_SEMAPHORES; - } - else - { - offset = 1; - sema_total = NUM_SPINLOCK_SEMAPHORES; - } - - idx = (counter++ % sema_total) + offset; - - /* double check we did things correctly */ - s_check_valid(idx); - - *lock = idx; -} - -void -s_unlock_sema(volatile slock_t *lock) -{ - int lockndx = *lock; - - s_check_valid(lockndx); - - PGSemaphoreUnlock(SpinlockSemaArray[lockndx - 1]); -} - -bool -s_lock_free_sema(volatile slock_t *lock) -{ - /* We don't currently use S_LOCK_FREE anyway */ - elog(ERROR, "spin.c does not support S_LOCK_FREE()"); - return false; -} - -int -tas_sema(volatile slock_t *lock) -{ - int lockndx = *lock; - - s_check_valid(lockndx); - - /* Note that TAS macros return 0 if *success* */ - return !PGSemaphoreTryLock(SpinlockSemaArray[lockndx - 1]); -} - -#endif /* !HAVE_SPINLOCKS */ |