linux-kernel - Re: [rfc 2/3] mm: vmscan: treat inactive cycling as neutral

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20111110160628.GM3153@redhat.com>
Date:	Thu, 10 Nov 2011 17:06:28 +0100
From:	Johannes Weiner <jweiner@...hat.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	Konstantin Khlebnikov <khlebnikov@...allels.com>,
	Pekka Enberg <penberg@...nel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Wu Fengguang <fengguang.wu@...el.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Rik van Riel <riel@...hat.com>, Mel Gorman <mel@....ul.ie>,
	Minchan Kim <minchan.kim@...il.com>,
	Gene Heskett <gene.heskett@...il.com>
Subject: Re: [rfc 2/3] mm: vmscan: treat inactive cycling as neutral

On Mon, Nov 07, 2011 at 11:34:17AM +0900, KAMEZAWA Hiroyuki wrote:
> On Wed, 2 Nov 2011 17:32:13 +0100
> Johannes Weiner <jweiner@...hat.com> wrote:
> 
> > Each page that is scanned but put back to the inactive list is counted
> > as a successful reclaim, which tips the balance between file and anon
> > lists more towards the cycling list.
> > 
> > This does - in my opinion - not make too much sense, but at the same
> > time it was not much of a problem, as the conditions that lead to an
> > inactive list cycle were mostly temporary - locked page, concurrent
> > page table changes, backing device congested - or at least limited to
> > a single reclaimer that was not allowed to unmap or meddle with IO.
> > More important than being moderately rare, those conditions should
> > apply to both anon and mapped file pages equally and balance out in
> > the end.
> > 
> > Recently, we started cycling file pages in particular on the inactive
> > list much more aggressively, for used-once detection of mapped pages,
> > and when avoiding writeback from direct reclaim.
> > 
> > Those rotated pages do not exactly speak for the reclaimability of the
> > list they sit on and we risk putting immense pressure on file list for
> > no good reason.
> > 
> > Instead, count each page not reclaimed and put back to any list,
> > active or inactive, as rotated, so they are neutral with respect to
> > the scan/rotate ratio of the list class, as they should be.
> > 
> > Signed-off-by: Johannes Weiner <jweiner@...hat.com>
> 
> I think this makes sense.
> 
> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
> 
> I wonder it may be better to have victim list for written-backed pages..

Do you mean an extra LRU list that holds dirty pages?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/