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Prevent lwlock dtrace probes from unnecessary work

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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
pull/71/head
Peter Eisentraut 4 years ago
parent 3eeadc425c
commit e48ce7ef0e
1 changed files with 26 additions and 13 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 39
      src/backend/storage/lmgr/lwlock.c

39
src/backend/storage/lmgr/lwlock.c
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@ -1323,7 +1323,8 @@ 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 (;;)
{
@ -1345,7 +1346,8 @@ 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");
@ -1354,7 +1356,8 @@ 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;
@ -1405,14 +1408,16 @@ 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;
}
@ -1484,7 +1489,8 @@ 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 (;;)
{
@ -1502,7 +1508,8 @@ 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");
@ -1532,7 +1539,8 @@ 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
{
@ -1540,7 +1548,8 @@ 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;
@ -1700,7 +1709,8 @@ 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 (;;)
{
@ -1719,7 +1729,8 @@ 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");
@ -1727,7 +1738,8 @@ LWLockWaitForVar(LWLock *lock, uint64 *valptr, uint64 oldval, uint64 *newval)
/* Now loop back and check the status of the lock again. */
}
TRACE_POSTGRESQL_LWLOCK_ACQUIRE(T_NAME(lock), LW_EXCLUSIVE);
if (TRACE_POSTGRESQL_LWLOCK_ACQUIRE_ENABLED())
TRACE_POSTGRESQL_LWLOCK_ACQUIRE(T_NAME(lock), LW_EXCLUSIVE);
/*
* Fix the process wait semaphore's count for any absorbed wakeups.
@ -1870,7 +1882,8 @@ LWLockRelease(LWLock *lock)
LWLockWakeup(lock);
}
TRACE_POSTGRESQL_LWLOCK_RELEASE(T_NAME(lock));
if (TRACE_POSTGRESQL_LWLOCK_RELEASE_ENABLED())
TRACE_POSTGRESQL_LWLOCK_RELEASE(T_NAME(lock));
/*
* Now okay to allow cancel/die interrupts.

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