| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | pgsql-committers(at)postgresql(dot)org |
| Subject: | pgsql: Micro optimize LWLockAttemptLock() a bit. |
| Date: | 2015-08-02 16:51:18 |
| Message-ID: | E1ZLwTm-0005Nv-GR@gemulon.postgresql.org |
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| Lists: | pgsql-committers |
Micro optimize LWLockAttemptLock() a bit.
LWLockAttemptLock pointlessly read the lock's state in every loop
iteration, even though pg_atomic_compare_exchange_u32() returns the old
value. Instead do that only once before the loop iteration.
Additionally there's no need to have the expected_state variable,
old_state mostly had the same value anyway.
Noticed-By: Heikki Linnakangas
Backpatch: 9.5, no reason to let the branches diverge at this point
Branch
------
REL9_5_STABLE
Details
-------
http://git.postgresql.org/pg/commitdiff/9074e41dbd41bc45ef79aeac1b6496bf087509a7
Modified Files
--------------
src/backend/storage/lmgr/lwlock.c | 20 ++++++++++++--------
1 file changed, 12 insertions(+), 8 deletions(-)
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