Re: posix advises ...
Zoltan Boszormenyi <[email protected]>
| Newsgroups | gmane.comp.db.postgresql.devel.patches |
|---|---|
| Message-ID | <[email protected]> |
Greg Smith írta: > On Thu, 19 Jun 2008, Zoltan Boszormenyi wrote: > >> This patch (revisited and ported to current CVS HEAD) is indeed using >> Greg's original patch and also added another patch written by Mark Wong >> that helps evicting closed XLOGs from memory faster. > > Great, that will save me some trouble. I've got a stack of Linux > performance testing queued up (got stuck behind a kernel bug impacting > pgbench) for the next couple of weeks and I'll include this in that > testing. I think I've got a similar class of hardware as you tested > on for initial evaluation--I'm getting around 200MB/s sequential I/O > right now out of my small RAID setup,. > > I added your patch to the queue for next month's CommitFest and listed > myself as the initial reviewer, but a commit that soon is unlikely. > Performance tests like this usually take a while to converge, and > since this is using a less popular API I expect a round of portability > concerns, too. > > Where did Marc's patch come from? I'd like to be able to separate out > that change from the rest if necessary. That patch was posted here: http://archives.postgresql.org/pgsql-patches/2008-03/msg00000.php > Also, if you have any specific test cases you ran that I could start > by trying to replicate a speedup on, those would be handy as well. We experienced synchronized seqscans slowing down after some (10+) clients which seems to be strange as it should be a strong selling point of 8.3. With the posix_fadvise() patchs, the dropoff was pushed further. The query involved multiple tables, it was not a trivial one table seqscan case. Without the patch, both a simpler SATA system (each disk at ~63MB/sec) and a hw RAID with 400+ MB/sec showed slowdown. The initial 60-63MB/sec with 1-3 clients on the single SATA disk system quickly dropped to 11-17MB/sec with more clients. With the patch, it only dropped to 40-47MB/sec. I cannot recall the RAID figures. > -- > * Greg Smith [email protected] http://www.gregsmith.com Baltimore, MD > -- ---------------------------------- Zoltán Böszörményi Cybertec Schönig & Schönig GmbH http://www.postgresql.at/ -- Sent via pgsql-patches mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-patches