Re: [patch] dynamic buffer cache hash table size

Heinz Mauelshagen (mauelsha@ez-darmstadt.telekom.de)
Mon, 25 Jan 1999 20:34:56 MET


>
> Hi,
>
> On Sat, 23 Jan 1999 0:00:23 MET, Heinz Mauelshagen
> <mauelsha@ez-darmstadt.telekom.de> said:
>
> > Have to do that test run later, but have a look at the already existing
> > one below.
>
> > Ingo Molnar asked me just today for a profile.
> > Most of the time is wasted in sync_buffers.
>

On Mon, 25 Jan 1999 16:55:50 GMT, Stephen C. Tweedie
<sct@redhat.com> answered:
>
> I am not surprised. Currently we have no way to flush completed
> writeback buffers off the LOCKED list and back onto the CLEAN list.
> sync() is therefore wandering over clean buffers all the time.
>
> Could you try the following patch (against 2.2.0-pre9)? It allows both
> sync and bdflush to refile such completed buffers back to the CLEAN
> list.
>

Hi Stephen.

Your patch is _great_.
It improves performance a lot.

Without it my test programs needed up to more than 30s with 120M buffermem
and up to 45s with 200M.

With your patch they need 1.5s/2.5s!!!
To compare: with little buffermem after reboot they need 0.3s.

This is a _must_ for 2.2.0!

Best regards,
Heinz

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