linux-kernel - Re: [PATCH] add some drop_caches documentation and info messsge

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Message-ID: <20121031174601.GI24389@liondog.tnic>
Date:	Wed, 31 Oct 2012 18:46:01 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Pavel Machek <pavel@....cz>
Cc:	Jiri Kosina <jkosina@...e.cz>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Dave Hansen <dave@...ux.vnet.ibm.com>,
	Michal Hocko <mhocko@...e.cz>, linux-mm@...ck.org,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] add some drop_caches documentation and info messsge

On Wed, Oct 31, 2012 at 06:31:54PM +0100, Pavel Machek wrote:
> Hmm? When I resume from hibernate, I want to use my machine.

Well, in my case with a workstation with 8 Gb, the only time the swapin
is noticeable is when I try to use firefox with a couple of dozens tabs
open. Once that thing is swapped in, system perf is back to normal.

I'll bet that even this slowdown would disappear if I use an SSD.

But I can imagine some workloads where swapping everything back in could
be discomforting.

> 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.).

That's a good idea, actually.

So, in any case, the current situation is fine as it is, I'd say: people
can decide whether they want to drop caches before suspending or not.
Problem solved.

Thanks.

-- 
Regards/Gruss,
    Boris.
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