Message-ID: <3C3F7FB2.225B6A7E@megsinet.net>
Date: Fri, 11 Jan 2002 18:13:38 -0600
From: "M.H.VanLeeuwen" <vanl@megsinet.net>
MIME-Version: 1.0
To: Ken Brownfield <brownfld@irridia.com>
CC: linux-kernel@vger.kernel.org
Subject: Re: [2.4.17/18pre] VM and swap - it's really unusable
In-Reply-To: <3C2CD326.100@athlon.maya.org> <20020103142301.C4759@asooo.flowerfire.com> <20020111144117.A1485@asooo.flowerfire.com>
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Ken Brownfield wrote:
> 
> After more testing, my original observations seem to be holding up,
> except that under heavy VM load (e.g., "make -j bzImage") the machine's
> overall performance seems far lower.  For instance, without the patch
> the -j build finishes in ~10 minutes (2x933P3/256MB) but with the patch
> I haven't had the patience to let it finish after more than an hour.
> 
> This is perhaps because the vmscan patch is too aggressively shrinking
> the caches, or causing thrashing in another area?  I'm also noticing
> that the amount of swap used is nearly an order of magnitude higher,
> which doesn't make sense at first glance...  Also, there are extended
> periods where idle CPU is 50-80%.
> 
> Maybe the patch or at least its intent can be merged with Andrea's work
> if applicable?
> 
> Thanks,
> --
> Ken.
> brownfld@irridia.com
> 


Ken,

Attached is an update to my previous vmscan.patch.2.4.17.c

Version "d" fixes a BUG due to a race in the old code _and_
is much less agressive at cache_shrinkage or conversely more
willing to swap out but not as much as the stock kernel.

It continues to work well wrt to high vm pressure.

Give it a whirl to see if it changes your "-j" symptoms.

If you like you can change the one line in the patch
from "DEF_PRIORITY" which is "6" to progressively smaller
values to "tune" whatever kind of swap_out behaviour you
like.

Martin
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