Re: performance "tests"

Tom Lane wrote:
> Raphael Bauduin <raphael(at)be(dot)easynet(dot)net> writes:
> > At some times, it seems to hang: it doesn't insert any rows for more
> > than 10 seconds. At that time, the postmaster process takes 0%. Why is
> > that?
>
> At a guess, you're seeing the syncer daemon flushing a lot of dirty
> kernel disk buffers out to disk, and thereby monopolizing disk I/O.
> I haven't experimented too much with Linux, but on HPUX it's not
> difficult for a sync() call to bring the system to its knees for many
> seconds, if you've got application programs that have written a whole
> lot of pages since the last sync.

Some BSD's implement trickle sync, for this very reason.

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