From: | "Merlin Moncure" <merlin(dot)moncure(at)rcsonline(dot)com> |
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To: | "Magnus Hagander" <mha(at)sollentuna(dot)net> |
Cc: | <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: |
Date: | 2005-02-16 13:42:12 |
Message-ID: | 6EE64EF3AB31D5448D0007DD34EEB3412A7624@Herge.rcsinc.local |
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Lists: | pgsql-hackers |
> 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.
The price on win32 for row level stats collector is fairly high. Also
the stats collector resets randomly under very high loads. However I
don't think this is what's going on here.
Also, IPC is out. The win32 IPC implementation is fine, if somewhat
slower than linux implementation. It's all about syncing, IMO.
Merlin
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