From cae610f0203ba485770e4d274378f3ab198dcc27 Mon Sep 17 00:00:00 2001 From: Peter Eisentraut Date: Thu, 29 Apr 2021 09:26:40 +0200 Subject: [PATCH] Prevent lwlock dtrace probes from unnecessary work If dtrace is compiled in but disabled, the lwlock dtrace probes still evaluate their arguments. Since PostgreSQL 13, T_NAME(lock) does nontrivial work, so it should be avoided if not needed. To fix, make these calls conditional on the *_ENABLED() macro corresponding to each probe. Reported-by: Craig Ringer Discussion: https://www.postgresql.org/message-id/CAGRY4nwxKUS_RvXFW-ugrZBYxPFFM5kjwKT5O+0+Stuga5b4+Q@mail.gmail.com --- src/backend/storage/lmgr/lwlock.c | 36 ++++++++++++++++++++----------- 1 file changed, 24 insertions(+), 12 deletions(-) diff --git a/src/backend/storage/lmgr/lwlock.c b/src/backend/storage/lmgr/lwlock.c index 975d547f34..55b9d7970e 100644 --- a/src/backend/storage/lmgr/lwlock.c +++ b/src/backend/storage/lmgr/lwlock.c @@ -1318,7 +1318,8 @@ LWLockAcquire(LWLock *lock, LWLockMode mode) #endif LWLockReportWaitStart(lock); - TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), mode); + if (TRACE_POSTGRESQL_LWLOCK_WAIT_START_ENABLED()) + TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), mode); for (;;) { @@ -1340,7 +1341,8 @@ LWLockAcquire(LWLock *lock, LWLockMode mode) } #endif - TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), mode); + if (TRACE_POSTGRESQL_LWLOCK_WAIT_DONE_ENABLED()) + TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), mode); LWLockReportWaitEnd(); LOG_LWDEBUG("LWLockAcquire", lock, "awakened"); @@ -1349,7 +1351,8 @@ LWLockAcquire(LWLock *lock, LWLockMode mode) result = false; } - TRACE_POSTGRESQL_LWLOCK_ACQUIRE(T_NAME(lock), mode); + if (TRACE_POSTGRESQL_LWLOCK_ACQUIRE_ENABLED()) + TRACE_POSTGRESQL_LWLOCK_ACQUIRE(T_NAME(lock), mode); /* Add lock to list of locks held by this backend */ held_lwlocks[num_held_lwlocks].lock = lock; @@ -1400,14 +1403,16 @@ LWLockConditionalAcquire(LWLock *lock, LWLockMode mode) RESUME_INTERRUPTS(); LOG_LWDEBUG("LWLockConditionalAcquire", lock, "failed"); - TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE_FAIL(T_NAME(lock), mode); + if (TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE_FAIL_ENABLED()) + TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE_FAIL(T_NAME(lock), mode); } else { /* Add lock to list of locks held by this backend */ held_lwlocks[num_held_lwlocks].lock = lock; held_lwlocks[num_held_lwlocks++].mode = mode; - TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE(T_NAME(lock), mode); + if (TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE_ENABLED()) + TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE(T_NAME(lock), mode); } return !mustwait; } @@ -1479,7 +1484,8 @@ LWLockAcquireOrWait(LWLock *lock, LWLockMode mode) #endif LWLockReportWaitStart(lock); - TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), mode); + if (TRACE_POSTGRESQL_LWLOCK_WAIT_START_ENABLED()) + TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), mode); for (;;) { @@ -1497,7 +1503,8 @@ LWLockAcquireOrWait(LWLock *lock, LWLockMode mode) Assert(nwaiters < MAX_BACKENDS); } #endif - TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), mode); + if (TRACE_POSTGRESQL_LWLOCK_WAIT_DONE_ENABLED()) + TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), mode); LWLockReportWaitEnd(); LOG_LWDEBUG("LWLockAcquireOrWait", lock, "awakened"); @@ -1527,7 +1534,8 @@ LWLockAcquireOrWait(LWLock *lock, LWLockMode mode) /* Failed to get lock, so release interrupt holdoff */ RESUME_INTERRUPTS(); LOG_LWDEBUG("LWLockAcquireOrWait", lock, "failed"); - TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT_FAIL(T_NAME(lock), mode); + if (TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT_FAIL_ENABLED()) + TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT_FAIL(T_NAME(lock), mode); } else { @@ -1535,7 +1543,8 @@ LWLockAcquireOrWait(LWLock *lock, LWLockMode mode) /* Add lock to list of locks held by this backend */ held_lwlocks[num_held_lwlocks].lock = lock; held_lwlocks[num_held_lwlocks++].mode = mode; - TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT(T_NAME(lock), mode); + if (TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT_ENABLED()) + TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT(T_NAME(lock), mode); } return !mustwait; @@ -1695,7 +1704,8 @@ LWLockWaitForVar(LWLock *lock, uint64 *valptr, uint64 oldval, uint64 *newval) #endif LWLockReportWaitStart(lock); - TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), LW_EXCLUSIVE); + if (TRACE_POSTGRESQL_LWLOCK_WAIT_START_ENABLED()) + TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), LW_EXCLUSIVE); for (;;) { @@ -1714,7 +1724,8 @@ LWLockWaitForVar(LWLock *lock, uint64 *valptr, uint64 oldval, uint64 *newval) } #endif - TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), LW_EXCLUSIVE); + if (TRACE_POSTGRESQL_LWLOCK_WAIT_DONE_ENABLED()) + TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), LW_EXCLUSIVE); LWLockReportWaitEnd(); LOG_LWDEBUG("LWLockWaitForVar", lock, "awakened"); @@ -1840,7 +1851,8 @@ LWLockRelease(LWLock *lock) /* nobody else can have that kind of lock */ Assert(!(oldstate & LW_VAL_EXCLUSIVE)); - TRACE_POSTGRESQL_LWLOCK_RELEASE(T_NAME(lock)); + if (TRACE_POSTGRESQL_LWLOCK_RELEASE_ENABLED()) + TRACE_POSTGRESQL_LWLOCK_RELEASE(T_NAME(lock)); /* * We're still waiting for backends to get scheduled, don't wake them up base-commit: 3a948ea0a2ced719f26e725b030558f2e4ab1d8e -- 2.31.1