From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758287AbcG0S5z (ORCPT ); Wed, 27 Jul 2016 14:57:55 -0400 Received: from shelob.surriel.com ([74.92.59.67]:33582 "EHLO shelob.surriel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758193AbcG0S5x (ORCPT ); Wed, 27 Jul 2016 14:57:53 -0400 Message-ID: <1469645861.10218.23.camel@surriel.com> Subject: Re: [PATCH 1/2] mm: page_alloc.c: Add tracepoints for slowpath From: Rik van Riel To: Michal Hocko Cc: Janani Ravichandran , linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, hannes@compxchg.org, vdavydov@virtuozzo.com, vbabka@suse.cz, mgorman@techsingularity.net, kirill.shutemov@linux.intel.com, bywxiaobai@163.com, rostedt@goodmis.org Date: Wed, 27 Jul 2016 14:57:41 -0400 In-Reply-To: <20160727184445.GG21859@dhcp22.suse.cz> References: <6b12aed89ad75cb2b3525a24265fa1d622409b42.1469629027.git.janani.rvchndrn@gmail.com> <20160727163351.GC21859@dhcp22.suse.cz> <1469643382.10218.20.camel@surriel.com> <20160727184445.GG21859@dhcp22.suse.cz> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-L20y8eXVuCaKErK+/ore" X-Mailer: Evolution 3.18.5.2 (3.18.5.2-1.fc23) Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-L20y8eXVuCaKErK+/ore Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2016-07-27 at 20:44 +0200, Michal Hocko wrote: > On Wed 27-07-16 14:16:22, Rik van Riel wrote: > >=20 > > On Wed, 2016-07-27 at 18:33 +0200, Michal Hocko wrote: > > >=20 > > > On Wed 27-07-16 10:47:59, Janani Ravichandran wrote: > > > >=20 > > > >=20 > > > > Add tracepoints to the slowpath code to gather some > > > > information. > > > > The tracepoints can also be used to find out how much time was > > > > spent in > > > > the slowpath. > > > I do not think this is a right thing to measure. > > > __alloc_pages_slowpath > > > is more a code organization thing. The fast path might perform an > > > expensive operations like zone reclaim (if node_reclaim_mode > 0) > > > so > > > these trace point would miss it. > > It doesn't look like it does. The fast path either > > returns an allocated page to the caller, or calls > > into the slow path. > I must be missing something here but what prevents > __alloc_pages_nodemask->get_page_from_freelist from doing > zone_reclaim? You are right! Guess the script may need to collect all the tracing output from __alloc_pages_nodemask on up, and then filter the output so only the interesting (read: long duration) traces get dumped out to a file. --=20 All rights reversed --=-L20y8eXVuCaKErK+/ore Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAABCAAGBQJXmQQmAAoJEM553pKExN6DlsEH/jDhmZz8jbCjaDvuE52Gr0DV 31gMd+1EwrLnBlo0AyxsdaiLtONjXs8ZJfybaaABMLnUclHPdqq/Zr5Ox7p3r3dR K5OBmB7R+vUpjrYxzMVHvw1WaTYseGWNOOjNdQyo2uRGe2MXQ0jRRAJ+Og+EMMvd 4SNX1mNFNKyZRlVbAv/DdRS3VKVdTi85oVjcctIIDETd7utt5MKhRWX2FoF+l2Ia NAJkqsQdsouNiLLHOdnnS1HqhUA0kx+6u1OVm47bd1PAu5qIYms3ocXeitic0e4o Udc5EO9JrTQy4eJPxPr1ie2i4cVF61Dg4MyZrCQWyinTV4eBCbWeHbMyfaCPRM8= =HeUd -----END PGP SIGNATURE----- --=-L20y8eXVuCaKErK+/ore--