From: Johannes Weiner <hannes@cmpxchg.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: kosaki.motohiro@jp.fujitsu.com, rjw@sisk.pl, riel@redhat.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 3/3][RFC] swsusp: shrink file cache first
Date: Sat, 7 Feb 2009 00:27:47 +0100 [thread overview]
Message-ID: <20090206232747.GA3539@cmpxchg.org> (raw)
In-Reply-To: <20090206130009.99400d43.akpm@linux-foundation.org>
On Fri, Feb 06, 2009 at 01:00:09PM -0800, Andrew Morton wrote:
> On Fri, 6 Feb 2009 05:49:07 +0100
> Johannes Weiner <hannes@cmpxchg.org> wrote:
>
> > > and, I think you should mesure performence result.
> >
> > Yes, I'm still thinking about ideas how to quantify it properly. I
> > have not yet found a reliable way to check for whether the working set
> > is intact besides seeing whether the resumed applications are
> > responsive right away or if they first have to swap in their pages
> > again.
>
> Describing your subjective non-quantitative impressions would be better
> than nothing...
Okay.
> The patch bugs me.
Please ignore it, it is broken as is. My verbal cortex got obviously
disconnected from my code cortex when writing the changelog... And I
will reconsider the actual change bits, I still think that we
shouldn't scan anon page lists while may_swap is zero.
> The whole darn point behind the whole darn page reclaim is "reclaim the
> pages which we aren't likely to need soon". There's nothing special
> about the swsusp code at all! We want it to do exactly what page
> reclaim normally does, only faster.
>
> So why do we need to write special hand-rolled code to implement
> something which we've already spent ten years writing?
>
> hm? And if this approach leads to less-than-optimum performance after
> resume then the fault lies with core page reclaim - it reclaimed the
> wrong pages!
>
> That actually was my thinking when I first worked on
> shrink_all_memory() and it did turn out to be surprisingly hard to
> simply reuse the existing reclaim code for this application. Things
> kept on going wrong. IIRC this was because we were freeing pages as we
> were reclaiming, so the page reclaim logic kept on seeing all these
> free pages and kept on wanting to bale out.
>
> Now, the simple and obvious fix to this is not to free the pages - just
> keep on allocating pages and storing them locally until we have
> "enough" memory. Then when we're all done, dump them all straight onto
> to the freelists.
>
> But for some reason which I do not recall, we couldn't do that.
>
> It would be good to revisit all this.
Thanks for the comments, I will see what I can come up with.
Hannes
next prev parent reply other threads:[~2009-02-06 23:28 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-06 3:11 [PATCH 0/3] [PATCH 0/3] swsusp: shrink file cache first Johannes Weiner
2009-02-06 3:11 ` [PATCH 1/3] swsusp: clean up shrink_all_zones() Johannes Weiner
2009-02-06 3:20 ` KOSAKI Motohiro
2009-02-06 3:11 ` [PATCH 2/3] swsusp: dont fiddle with swappiness Johannes Weiner
2009-02-06 3:21 ` KOSAKI Motohiro
2009-02-06 3:11 ` [PATCH 3/3][RFC] swsusp: shrink file cache first Johannes Weiner
2009-02-06 3:39 ` KOSAKI Motohiro
2009-02-06 4:49 ` Johannes Weiner
2009-02-06 5:59 ` KOSAKI Motohiro
2009-02-06 12:24 ` Johannes Weiner
2009-02-06 13:35 ` MinChan Kim
2009-02-06 17:15 ` MinChan Kim
2009-02-06 23:37 ` Johannes Weiner
2009-02-09 19:43 ` [patch] vmscan: rename sc.may_swap to may_unmap Johannes Weiner
2009-02-09 23:02 ` MinChan Kim
2009-02-10 10:00 ` KOSAKI Motohiro
2009-03-27 6:19 ` [PATCH] vmscan: memcg needs may_swap (Re: [patch] vmscan: rename sc.may_swap to may_unmap) Daisuke Nishimura
2009-03-27 6:30 ` KAMEZAWA Hiroyuki
2009-03-29 23:45 ` KOSAKI Motohiro
2009-03-31 0:18 ` Daisuke Nishimura
2009-03-31 1:26 ` Minchan Kim
2009-03-31 1:42 ` KAMEZAWA Hiroyuki
2009-03-31 1:48 ` KOSAKI Motohiro
2009-04-01 4:09 ` Johannes Weiner
2009-04-01 5:08 ` Daisuke Nishimura
2009-04-01 9:04 ` KAMEZAWA Hiroyuki
2009-04-01 9:11 ` KOSAKI Motohiro
2009-04-01 9:49 ` Johannes Weiner
2009-04-01 9:55 ` KOSAKI Motohiro
2009-04-01 16:03 ` Johannes Weiner
2009-03-31 1:52 ` Daisuke Nishimura
2009-02-06 21:00 ` [PATCH 3/3][RFC] swsusp: shrink file cache first Andrew Morton
2009-02-06 23:27 ` Johannes Weiner [this message]
2009-02-07 17:23 ` Rafael J. Wysocki
2009-02-08 20:56 ` Johannes Weiner
2009-02-07 4:41 ` Nigel Cunningham
2009-02-07 16:51 ` KOSAKI Motohiro
2009-02-07 21:20 ` Nigel Cunningham
2009-02-27 13:27 ` Pavel Machek
2009-03-01 10:37 ` KOSAKI Motohiro
2009-02-06 8:03 ` MinChan Kim
2009-02-06 10:06 ` MinChan Kim
2009-02-06 11:50 ` Johannes Weiner
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