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From: Pavel Machek <pavel@ucw.cz>
To: Borislav Petkov <bp@alien8.de>, Jiri Kosina <jkosina@suse.cz>,
	Andrew Morton <akpm@linux-foundation.org>,
	"Rafael J. Wysocki" <rjw@sisk.pl>,
	Dave Hansen <dave@linux.vnet.ibm.com>,
	Michal Hocko <mhocko@suse.cz>,
	linux-mm@kvack.org,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] add some drop_caches documentation and info messsge
Date: Wed, 31 Oct 2012 18:31:54 +0100	[thread overview]
Message-ID: <20121031173154.GA20660@elf.ucw.cz> (raw)
In-Reply-To: <20121029095819.GA4326@liondog.tnic>

On Mon 2012-10-29 10:58:19, Borislav Petkov wrote:
> On Mon, Oct 29, 2012 at 09:59:59AM +0100, Jiri Kosina wrote:
> > You might or might not want to do that. Dropping caches around suspend
> > makes the hibernation process itself faster, but the realtime response
> > of the applications afterwards is worse, as everything touched by user
> > has to be paged in again.

Also note that page-in is slower than  reading hibernation image,
because it is not compressed, and involves seeking.

> Right, do you know of a real use-case where people hibernate, then
> resume and still care about applications response time right afterwards?

Hmm? When I resume from hibernate, I want to use my
machine. *Everyone* cares about resume time afterwards. You move your
mouse, and you don't want to wait for X to be paged-in.

> Besides, once everything is swapped back in, perf. is back to normal,
> i.e. like before suspending.

Kernel will not normally swap anything in automatically. Some people
do swapoff -a; swapon -a to work around that. (And yes, maybe some
automatic-swap-in-when-there's-plenty-of-RAM would be useful.).
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

  parent reply	other threads:[~2012-10-31 17:31 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-10-12 12:57 [PATCH] add some drop_caches documentation and info messsge Michal Hocko
2012-10-12 18:54 ` KOSAKI Motohiro
2012-10-15  9:04 ` Kamezawa Hiroyuki
2012-10-15 14:05 ` Dave Hansen
2012-10-23 23:45 ` Andrew Morton
2012-10-24  6:29   ` Michal Hocko
2012-10-24 19:54     ` Andrew Morton
2012-10-24 20:28       ` Dave Hansen
2012-10-24 20:48         ` Andrew Morton
2012-10-24 21:06           ` Borislav Petkov
2012-10-24 21:13             ` Andrew Morton
2012-10-24 22:04               ` Rafael J. Wysocki
2012-10-25  1:17                 ` Andrew Morton
2012-10-25 20:16                   ` Rafael J. Wysocki
2012-10-29  8:59                   ` Jiri Kosina
2012-10-29  9:58                     ` Borislav Petkov
2012-10-29 10:01                       ` Jiri Kosina
2012-10-29 10:11                         ` Borislav Petkov
2012-10-31 17:31                       ` Pavel Machek [this message]
2012-10-31 17:46                         ` Borislav Petkov
2012-10-24 22:35               ` KOSAKI Motohiro
2012-10-25 14:21                 ` Michal Hocko
2012-10-24 21:18             ` Dave Hansen
2012-10-24 22:48               ` Borislav Petkov
2012-10-24 22:57                 ` Dave Hansen
2012-10-25  0:56                   ` KOSAKI Motohiro
2012-10-25  9:24                     ` Borislav Petkov
2012-10-25 11:57                       ` Dave Hansen
2012-10-25 14:24                         ` Borislav Petkov
2012-10-25 14:25                         ` Michal Hocko
2012-10-26  7:45           ` Mika Boström
2012-11-01 20:26           ` Pavel Machek
2012-10-25 14:09       ` Michal Hocko

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