Re: - Mailing list pgsql-hackers

From Merlin Moncure
Subject Re:
Date
Msg-id 6EE64EF3AB31D5448D0007DD34EEB3412A7624@Herge.rcsinc.local
Whole thread Raw
In response to  ("E.Rodichev" <er@sai.msu.su>)
List 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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