From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Con Kolivas <kernel@kolivas.org>
Subject: Re: [PATCH] mm: swsusp shrink_all_memory tweaks
Date: Thu, 30 Mar 2006 22:57:24 +0200
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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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