From: Con Kolivas <kernel@kolivas.org>
To: Pavel Machek <pavel@suse.cz>
Subject: Re: does swsusp suck after resume for you?
Date: Fri, 17 Mar 2006 08:33:26 +1100
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Cc: ck@vds.kolivas.org, Stefan Seyfried <seife@suse.de>,
       Jun OKAJIMA <okajima@digitalinfra.co.jp>, linux-kernel@vger.kernel.org,
       Andreas Mohr <andi@rhlx01.fht-esslingen.de>,
       "Rafael J. Wysocki" <rjw@sisk.pl>
References: <200603101704.AA00798@bbb-jz5c7z9hn9y.digitalinfra.co.jp> <200603162147.56725.kernel@kolivas.org> <20060316105054.GB9399@atrey.karlin.mff.cuni.cz>
In-Reply-To: <20060316105054.GB9399@atrey.karlin.mff.cuni.cz>
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> > > > The tunable in /proc/sys/vm/swap_prefetch is now bitwise ORed:
> > > > Thus if you set this value 
> > > > to 3 it will prefetch aggressively and then drop back to the default
> > > > of 1. This makes it easy to simply set the aggressive flag once and
> > > > forget about it. I've booted and tested this feature and it's working
> > > > nicely. Where exactly you'd set this in your resume scripts I'm not
> > > > sure. A rolled up patch against 2.6.16-rc6-mm1 is here for
> > > > simplicity:

correct url:
http://ck.kolivas.org/patches/swap-prefetch/2.6.16-rc6-mm1-swap_prefetch_test.patch

> > 2 means aggressively prefetch as much as possible and then disable swap
> > prefetching from that point on. Too confusing?
>
> Ahha... oops, yes, clever; no, I guess keep it.

Ok the patch works fine for me and the feature is worthwhile in absolute terms 
as well as for improving resume. 

Pavel, while we're talking about improving behaviour after resume I had a look 
at the mechanism used to free up ram before suspending and I can see scope 
for some changes in the vm code that would improve the behaviour after 
resuming. Is the mechanism used to free up ram going to continue being used 
with uswsusp? If so, I'd like to have a go at improving the free up ram vm 
code to make it behave nicer after resume. I have some ideas about how best 
to free up ram differently from normal reclaim which would improve behaviour 
post resume.

Cheers,
Con
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