From: Andrew Morton <akpm@osdl.org>
To: Con Kolivas <kernel@kolivas.org>
Cc: linux-kernel@vger.kernel.org, ck@vds.kolivas.org
Subject: Re: [PATCH] vm - swap_prefetch v12
Date: Thu, 29 Sep 2005 16:24:02 -0700 [thread overview]
Message-ID: <20050929162402.71eee9c2.akpm@osdl.org> (raw)
In-Reply-To: <200509300912.58722.kernel@kolivas.org>
Con Kolivas <kernel@kolivas.org> wrote:
>
> On Fri, 30 Sep 2005 07:54 am, Andrew Morton wrote:
> > Con Kolivas <kernel@kolivas.org> wrote:
> > > Once pages have been added to the swapped list, a timer is started,
> > > testing for conditions suitable to prefetch swap pages every 5 seconds.
> > > Suitable conditions are defined as lack of swapping out or in any pages,
> > > and no watermark tests failing. Significant amounts of dirtied ram also
> > > prevent prefetching. It then checks that we have spare ram looking for at
> > > least 3* pages_high free per zone and if it succeeds that will prefetch
> > > pages from swap.
> >
> > Did you consider poking around in gendisk.disk_stats to determine whether
> > the swap disk(s) are idleish?
>
> I didn't know where to look for that info. Thanks! I'm open to *any*
> suggestions and I'll look into it as I can't take this code much further
> without outside help.
>
Might also be able to utilise CFQ's I/O priorities. That should be more
efective than a heuristic based on disk_stats, however you'd probably need
to work out whether the swapdev actually supports IO priorities and I'm not
sure how one would query that (cleanly).
next prev parent reply other threads:[~2005-09-29 23:24 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-29 15:15 Con Kolivas
2005-09-29 21:54 ` Andrew Morton
2005-09-29 23:12 ` Con Kolivas
2005-09-29 23:24 ` Andrew Morton [this message]
2005-09-29 23:42 ` Con Kolivas
2005-09-29 23:52 ` Andrew Morton
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