Re: does swsusp suck after resume for you?

Pavel Machek
2006-03-20T08:56:53Z

On Pá 17-03-06 08:33:26, Con Kolivas wrote:
> > > > > 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

I'm sorry, I'm leaving for mountains tommorow, so it will take me a
while to test it.

> > > 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.

Good.

> 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

Yes, it is.

> 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.

One possible improvement would be to never ever return 0 if there can
still be more memory freed. Rafael did some ugly workaround, but we
do not even understand the problem.
Pavel
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82: return SampleTable;