From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757036AbaEPKUu (ORCPT ); Fri, 16 May 2014 06:20:50 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:52554 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757019AbaEPKUt (ORCPT ); Fri, 16 May 2014 06:20:49 -0400 Date: Fri, 16 May 2014 12:20:43 +0200 From: Peter Zijlstra To: Ben Segall Cc: Ingo Molnar , linux-kernel@vger.kernel.org Subject: Re: [PATCH] sched: fix exec_start/task_hot on migrated tasks Message-ID: <20140516102043.GT30445@twins.programming.kicks-ass.net> References: <20140515225920.7179.13924.stgit@sword-of-the-dawn.mtv.corp.google.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="Lw/GBiv4LoRdT+hF" Content-Disposition: inline In-Reply-To: <20140515225920.7179.13924.stgit@sword-of-the-dawn.mtv.corp.google.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --Lw/GBiv4LoRdT+hF Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, May 15, 2014 at 03:59:20PM -0700, Ben Segall wrote: > task_hot checks exec_start on any runnable task, but if it has been > migrated since the it last ran, then exec_start is a clock_task from > another cpu. If the old cpu's clock_task was sufficiently far ahead of > this cpu's then the task will not be considered for another migration > until it has run. Instead reset exec_start whenever a task is migrated, > since it is presumably no longer hot anyway. >=20 > Signed-off-by: Ben Segall > --- > kernel/sched/fair.c | 3 +++ > 1 file changed, 3 insertions(+) >=20 > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 28ccf50..9f8dfeb 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -4544,6 +4544,9 @@ migrate_task_rq_fair(struct task_struct *p, int nex= t_cpu) > atomic_long_add(se->avg.load_avg_contrib, > &cfs_rq->removed_load); > } > + > + /* We have migrated, no longer consider this task hot */ > + se.exec_start =3D 0; se->exec_start compiles loads better --Lw/GBiv4LoRdT+hF Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJTdeZ7AAoJEHZH4aRLwOS6ATsQAJHbEAkkUed5KzX0KYoYbDGD tiYS59HOVidHXGVAThoYN97XIqkpO2hVtsCF6sNMWn1zwfBg6sJv2CFtTQDZPe40 7hAplKgJeWIzD65h1BwZrYmpF4sjaQpo/ftr/zScBI1P7GAJeElHWSywFE+dDx/W l5h+ROt41noSfimPGeo8wYWWrBGHQzJjwQmOwgn0k5VZ2PH5Yr63bC4vXDtQNO5U FJfn6CEu+Q0Ox8wvMTgnD7uhvnNIhre1yM8IWI1Xdv7BWTilk5CLraXLVLYbaVp5 xFQhZG5u+gxwYVgHgbhQEq3inweFi2sjeqmZjlmBZeCNCRH0JbFmAPPR0GceQYV4 5ueKXrzmTDche/OK6EgIpPkoDzyPvwVEoyfzv2r+q431R6+HjtMtBNiI5RGiAqo7 /ADW6fOjFKXZlDWKpGkbo2W2z9E0HSNDaLekKxO8YYl9cCFizW1d2r5nTMFXx+SU agVzEkdjliiL4Gsre/+fF2nepm0rVTM0f4KvwIY6ZPW86+ecWjs8+zcN2MaTJYXg GcGjT0SXcBE0VkndPaLcTClwjaoHf1V4JHr2BZ/LAtaqikMJmRn10p2G5GL9i8MO lxrI0kiRKkhWKWR0ghMzwujI/lhqAoS6u0XQuUUHuWl6qjI7B+UJB7lbvGdaZpyr HqqgWay/WIt54+VDRsFw =yOpt -----END PGP SIGNATURE----- --Lw/GBiv4LoRdT+hF--