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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.

Reviewed-by: Craig Ringer <craig.ringer@enterprisedb.com>
Discussion: https://www.postgresql.org/message-id/CAGRY4nwxKUS_RvXFW-ugrZBYxPFFM5kjwKT5O+0+Stuga5b4+Q@mail.gmail.com
This commit is contained in:
Peter Eisentraut 2021-05-03 12:11:33 +02:00
parent c285babf8f
commit b94409a02f
1 changed files with 24 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
src/backend/storage/lmgr/lwlock.c
View File

@ -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