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From: Pasi Savolainen <psavo@iki.fi>
Subject: Re: swapspace layout improvements advocacy
Date: Sat, 15 Jan 2005 08:55:08 +0000 (UTC)
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* Barry K. Nathan <barryn@pobox.com>:
> On Fri, Jan 14, 2005 at 02:55:27PM +0100, Tim Schmielau wrote:
>> 2.6 seems in due need of such a patch.
>> 
>> I recently found out that 2.6 kernels degrade horribly when going into 
>> swap. On my dual PIII-850 with as little as 256 mb ram, I can easily 
> [snip]
>
> I haven't tried the patch in question (unless it's in any Fedora
> kernels), but I've noticed that the single biggest step to improve
> swapping performance in 2.6 is to use the CFQ scheduler, not the AS
> scheduler. (That's also why Red Hat/Fedora kernels use CFQ as the
> default scheduler.)

I've not tried the patch yet, but with 1G mem / 1G swap when I finally
hit the swap and quit the program that uses it (straw, gimp..), machine
will stop responding for 10-15sec. 
I have 'elevator=cfq' in boot command and this is SMP. Last seen
yesterday when shutting down 2.6.10-rc2-mm4 to try out latest -mm.
I did vmstat runs a while ago, but didn't see anything really out of
line, maybe it didn't get data either (or I don't know what is normal).


-- 
   Psi -- <http://www.iki.fi/pasi.savolainen>