Re:

From: "Magnus Hagander" <mha(at)sollentuna(dot)net>
To: "E(dot)Rodichev" <er(at)sai(dot)msu(dot)su>, <pgsql-hackers(at)postgresql(dot)org>
Cc: <oleg(at)sai(dot)msu(dot)su>
Subject: Re:
Date: 2005-02-15 16:33:02
Message-ID: 6BCB9D8A16AC4241919521715F4D8BCE4768A2@algol.sollentuna.se
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> I've tested the performance of 8.0.1 at my dual-boot notebook
> (Linux and Windows XP).
>
> I installed 8.0.1 for Linux and Windows XP, and run pgbench
> -c 1 -t 1000 Under Linux (kernel 2.6.10) I got about 800 tps,
> and under Windows XP - about 20-24 tps.
>
> Next I switched off virtual memory under Windows (as it was
> recommended in posting
> http://www.pgsql.ru/db/mw/msg.html?mid=2026070) It does not
> help. Without virtual memory I got 15-17 tps.

Question 1: Is your writeback cache really disabled in Linux, on the
harddrive? Windows fsync will *write through the disk write cache* if
the driver is properly implemented. AFAIK, on Linux if write cache is
enabled on the drive, fsync will only get into the cache.
800tps sounds unreasonably high on a notebook.

Question 2: Please try disabling the stats connector and see if that
helps. Merlin Moncure reported some scalability issues with the stats
collector previously.

> Several yeas ago (about 1997-1998) Oleg Bartunov and me had
> the same performance results (Linux vs Windows NT + cygwin).
> It was the discussion at this list with resume that the
> reason is the implementation of shared memory under Windows.
> Every IPC operation results the HDD access.

It shouldn't in 8.0 - at least not on the native win32. Don't know about
cygwin.

//Magnus

Responses

  • Re: at 2005-02-15 17:03:39 from E.Rodichev
  • Re: at 2005-02-15 17:09:42 from Matthew T. O'Connor

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