Re: [PATCH] mm: swsusp shrink_all_memory tweaks

From: Rafael J. Wysocki
Date: Thu Mar 30 2006 - 15:55:47 EST


On Thursday 30 March 2006 22:38, Con Kolivas wrote:
> On Friday 31 March 2006 03:12, Rafael J. Wysocki wrote:
> > OK, I have the following observations:
>
> Thanks.
> >
> > 1) The patch generally causes more memory to be freed during suspend than
> > the unpatched code (good).
>
> Yes I know you meant less, that's good.
>
> > 2) However, if more than 50% of RAM is used by application data, it causes
> > the swap prefetch to trigger during resume (that's an impression; anyway
> > the system swaps in a lot at that time), which takes some time (generally
> > it makes resume 5-10s longer on my box).
>
> Is that with this "swsusp shrink_all_memory tweaks" patch alone? It doesn't
> touch swap prefetch.

Still swap prefetch is present in -mm so it can be triggered incidentally
I think.

> > 3) The problem with returning zero prematurely has not been entirely
> > eliminated. It's happened for me only once, though.
>
> Probably hard to say, but is the system in any better state after resume has
> completed?

It seems so, but it also depends on the (actual) image size, memory usage
before suspend etc. Well ...

> That was one of the aims. Also a major part of this patch is a cleanup of
> the hot balance_pgdat function as well, which suspend no longer touches with
> this patch.

I think the patch is a good idea overall, but it needs some more testing.
I'll try to figure out a way to measure its performance, so we have some
hard data to discuss.

Greetings,
Rafael
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