From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754745AbbCaN0H (ORCPT ); Tue, 31 Mar 2015 09:26:07 -0400 Received: from prod-mail-xrelay02.akamai.com ([72.246.2.14]:40493 "EHLO prod-mail-xrelay02.akamai.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754024AbbCaNXH (ORCPT ); Tue, 31 Mar 2015 09:23:07 -0400 Date: Tue, 31 Mar 2015 09:23:05 -0400 From: Eric B Munson To: Andrew Morton Cc: Jonathan Corbet , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Document interaction between compaction and the unevictable LRU Message-ID: <20150331132305.GC17678@akamai.com> References: <1427740274-2926-1-git-send-email-emunson@akamai.com> <20150330150939.2e0bd53a3a16ada4cce8ec05@linux-foundation.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="/Uq4LBwYP4y1W6pO" Content-Disposition: inline In-Reply-To: <20150330150939.2e0bd53a3a16ada4cce8ec05@linux-foundation.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --/Uq4LBwYP4y1W6pO Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, 30 Mar 2015, Andrew Morton wrote: > On Mon, 30 Mar 2015 14:31:14 -0400 Eric B Munson wro= te: >=20 > > The memory compaction code uses the migration code to do most of the > > work in compaction. However, the compaction code interacts with the > > unevictable LRU differently than migration code and this difference > > should be noted in the documentation. > >=20 > > --- a/Documentation/vm/unevictable-lru.txt > > +++ b/Documentation/vm/unevictable-lru.txt > > @@ -450,6 +451,16 @@ list because of a race between munlock and migrati= on, page migration uses the > > putback_lru_page() function to add migrated pages back to the LRU. > > =20 > > =20 > > +COMPACTING MLOCKED PAGES > > +------------------------ > > + > > +The unevictable LRU can be scanned for compactable regions and the def= ault > > +behavior is to do so. There is a sysctl to control this behavior (see > > +Documentation/sysctl/vm.txt). Once scanning of the unevictable LRU is > > +enabled, the work of compaction is mostly handled by the page migratio= n code > > +and the same work flow as described in MIGRATING MLOCKED PAGES will ap= ply. > > + >=20 > Thanks. Let's tell people what this sysctl is called? >=20 >=20 > s@There is a sysctl to control@/proc/sys/vm/compact_unevictable_allowed c= ontrols@: >=20 > --- a/Documentation/vm/unevictable-lru.txt~document-interaction-between-c= ompaction-and-the-unevictable-lru-fix > +++ a/Documentation/vm/unevictable-lru.txt > @@ -455,10 +455,11 @@ COMPACTING MLOCKED PAGES > ------------------------ > =20 > The unevictable LRU can be scanned for compactable regions and the defau= lt > -behavior is to do so. There is a sysctl to control this behavior (see > -Documentation/sysctl/vm.txt). Once scanning of the unevictable LRU is > -enabled, the work of compaction is mostly handled by the page migration = code > -and the same work flow as described in MIGRATING MLOCKED PAGES will appl= y. > +behavior is to do so. /proc/sys/vm/compact_unevictable_allowed controls > +this behavior (see Documentation/sysctl/vm.txt). Once scanning of the > +unevictable LRU is enabled, the work of compaction is mostly handled by > +the page migration code and the same work flow as described in MIGRATING > +MLOCKED PAGES will apply. > =20 > =20 > mmap(MAP_LOCKED) SYSTEM CALL HANDLING > _ >=20 That looks good, thanks. Eric --/Uq4LBwYP4y1W6pO Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJVGp+5AAoJELbVsDOpoOa9Zl0P/i5CdNXPOV/z727TIzkZm2AV 3DIN7EcQrEz/bRnhbtFjj196vOmo8ef6ddxftr4hUh+ISTB42Ssx5LT4zQEMaxgp naisYmi192H3lnMgRYjCAEpNlPx+MjJI+bcOGVJp7WmnhEq7E/DMXAVmELZdYPoi 6JSd+DF3kl7XnQfNonDHceRVQUf7nz8Qt+O+tKf3Wrp+CCQuiGfJuVMNVmagLbPA apiJnpSfoUuHRnP2N/60uHozFLnI4Zbfuuk8UYVk09srtCCZoL30x/Z1Ds/vkFeA MhW88MTfNeNayYn1bhfUGurn6IG2/y7KxrEKUrvKJpMrZaoLjZVw1BmPT74Ulf62 GKcmg7PO4LWCW4e/GEMLW3073ax/RiVO6Vno4efGjUEEO6kL212JkabBRsdsdCoi 8KPsj9IVska+w5sFm/X8tKVIhnjHSD6CQHwfaxy8wAfo2GasxsMDTdHYRSdxxzhf T/pV8u1iGsuwRwCXFdfpdppgU8kxj3qbz9dpyljvq9YczpYlPrfmDQJunfbD9MHb xyOO+25IJEo/hEs7JITLLSCrTRvlsD7NHFZw69QANtvopXEJp1EktuzwXvM/HEnB 4551bj6uT9Gw6azGeslF8jINkr1nOQlpPW1LcajWZPrtfdik504wqeJnPalZBu4y zMU3vahwe5Igl9bwaMNH =eIuD -----END PGP SIGNATURE----- --/Uq4LBwYP4y1W6pO--