On 2.3.2012 03:05, Claudio Freire wrote: > On Thu, Mar 1, 2012 at 10:13 PM, Tomas Vondra <tv@xxxxxxxx> wrote: >> >> Maybe. I still am not sure how fsync=off affects the eviction in your >> opinion. I think it does not (or just very remotely) and you were saying >> the opposite. IMHO the eviction of (dirty) buffers is either very fast >> or slow, no matter what the fsync setting is. > > I was thinking page cleanup, but if you're confident it doesn't happen > on a read-only database, I'd have to agree on all your other points. > > I have seen a small amount of writes on a read-only devel DB I work > with, though. Usually in the order of 100kb/s writes per 10mb/s reads > - I attributed that to page cleanup. In that case, it can add some > wait time to fsync, even though it's really a slow volume of writes. > If you're right, I'm thinking, it may be some other thing... atime > updates maybe, I'd have to check the filesystem configuration I guess. I'd guess those writes were caused by hint bits (~ page cleanup, but that's a one-time thing and should be fixed by VACUUM FREEZE right after the load). Or maybe it was related to runtime stats (i.e. pgstat). T. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
