On 2016-03-31 20:21:02 +0300, Alexander Korotkov wrote: > ! BEGIN_BUFSTATE_CAS_LOOP(bufHdr); > > ! Assert(BUF_STATE_GET_REFCOUNT(state) > 0); > ! wasDirty = (state & BM_DIRTY) ? true : false; > ! state |= BM_DIRTY | BM_JUST_DIRTIED; > ! if (state == oldstate) > ! break;
I'm doubtful that this early exit is entirely safe. None of the preceding operations imply a memory barrier. The buffer could previously have been marked dirty, but cleaned since. It's pretty critical that we re-set the dirty bit (there's no danger of loosing it with a barrier, because we hold an exclusive content lock). Practically the risk seems fairly low, because acquiring the exclusive content lock will have implied a barrier. But it seems unlikely to have a measurable performance effect to me, so I'd rather not add the early exit. Andres -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
