From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755181AbaEHQNl (ORCPT ); Thu, 8 May 2014 12:13:41 -0400 Received: from casper.infradead.org ([85.118.1.10]:44571 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754600AbaEHQNk (ORCPT ); Thu, 8 May 2014 12:13:40 -0400 Date: Thu, 8 May 2014 18:13:37 +0200 From: Peter Zijlstra To: minyard@acm.org Cc: Ingo Molnar , linux-kernel@vger.kernel.org, Corey Minyard Subject: Re: [PATCH] sched: Initialize rq->age_stamp on processor start Message-ID: <20140508161337.GF30445@twins.programming.kicks-ass.net> References: <1399405857-14056-1-git-send-email-minyard@acm.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="yKmnPmKxJBqIz68t" Content-Disposition: inline In-Reply-To: <1399405857-14056-1-git-send-email-minyard@acm.org> 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 --yKmnPmKxJBqIz68t Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, May 06, 2014 at 02:50:57PM -0500, minyard@acm.org wrote: > From: Corey Minyard >=20 > If the sched_clock time starts at a large value, the kernel will spin > in sched_avg_update for a long time while rq->age_stamp catches up > with rq->clock. >=20 > The comment in kernel/sched/clock.c says that there is no strict promise > that it starts at zero. So initialize rq->age_stamp when a cpu starts up > to avoid this. >=20 > I was seeing long delays on a simulator that didn't start the clock at > zero. This might also be an issue on reboots on processors that don't > re-initialize the timer to zero on reset, and when using kexec. >=20 > Signed-off-by: Corey Minyard This patch made my cris-defconfig build fail. --yKmnPmKxJBqIz68t Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJTa60wAAoJEHZH4aRLwOS6YxIP/3EmOvvP1+1mNNhOl4wIU/n/ t7E9ztjkqEu2qiJ4XN9MaI/bDJmmYDIKPkFK6CEY4FnfYkZsY6c8CYnr5CYX0Wu1 maCrZXNstkYr0LQvXw+nH8ZqzabKtyFAUcTB0m3Pc+ouIyNeis+cWHPSQmNHv97O B6clDgRV8v2LdyY4fcewgHj2RJPeoRopf45htb2Ks1Xig0yGJldhDi6dxWX2LYLU bteRmZrFUnNEhUa8gnIA0vQghJ1zTosR0ZAg+SY+iafpnVdemCPPQ2V5vztfFxLW ixC+U+UWc+8iw+fYcCfsob0X7XeA4FYMk7PT6+XMC0cTSIf+W/OpdXA2qrOuaMg8 tvMSVAoI+OR8b3YBsBMOH38/uBxRTFHuuLfF6rE/Ne9DmskVC7E1wdMi2mBSfGX3 s3/Uk/sbO4FZqjEVBWZT9e3ybcDtZoEam0NbMyyg/0uyVrrIdk6QLIGgtfAOZaXJ jxsFfUwc//x0MhkzLXA0AYKL5sjnMQq3ODNCpaKLJXAo5tkMbAQn9SKV5JYee9K0 TEGOOyL1Hyu/eUQsHIpGvF6KfaOjEnu9OZB4zey78C3Qf7BKJPBd/CRq+rFE7TrG Fhw0pde9qATNJXd+aoOrt495rO4nuUZMpJvLwNkn6bc0g4PthRnhSMlEjpR7eUST 9QkJOkLHG4kv/1FGX+E+ =1Wrk -----END PGP SIGNATURE----- --yKmnPmKxJBqIz68t--