Re: swsusp: how much memory to free? [was Re: swsusp performance problems in 2.6.15-rc3-mm1]

From: Pavel Machek
Date: Wed Dec 07 2005 - 06:59:38 EST


Hi!

> > > OTOH, we can get similar result by just making the kernel free some
> > > more memory _after_ we are sure we have enough memory to suspend.
> > > IOW, after the code that's currently in swsusp_shrink_memory() has finished,
> > > we can try to free some "extra" memory to improve performance, if
> > > needed. The question is how much "extra" memory should be freed and
> > > I'm afraid it will have to be tuned on the per-system, or at least
> > > per-RAM-size, basis.
> >
> > I'd prefer not to have extra tunables. "Write only 500MB" will work
> > okay for common desktop users -- as long as common desktop fits into
> > 500MB, that is. "Free not used in last 10 minutes" should work okay
> > for everyone, but may be slightly harder to implement.
>
> Still, it can be done with a fairly small patch that has an additional
> advantage, as it allows us to get rid of the FAST_FREE constant
> which I don't like. Appended (untested).

Looks good to me.

> Index: linux-2.6.15-rc5-mm1/kernel/power/swsusp.c
> ===================================================================
> --- linux-2.6.15-rc5-mm1.orig/kernel/power/swsusp.c 2005-12-05 22:07:12.000000000 +0100
> +++ linux-2.6.15-rc5-mm1/kernel/power/swsusp.c 2005-12-07 12:40:27.000000000 +0100
> @@ -626,6 +626,7 @@
>
> int swsusp_shrink_memory(void)
> {
> + unsigned long size;
> long tmp;

Perhaps both should be long, or both unsigned long?

Pavel
--
Thanks, Sharp!
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