Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932105AbbLDL4m (ORCPT ); Fri, 4 Dec 2015 06:56:42 -0500 Received: from terminus.zytor.com ([198.137.202.10]:60192 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752349AbbLDL4j (ORCPT ); Fri, 4 Dec 2015 06:56:39 -0500 Date: Fri, 4 Dec 2015 03:55:48 -0800 From: tip-bot for Frederic Weisbecker Message-ID: Cc: peterz@infradead.org, hpa@zytor.com, efault@gmx.de, linux-kernel@vger.kernel.org, paulmck@linux.vnet.ibm.com, lcapitulino@redhat.com, mingo@kernel.org, riel@redhat.com, tglx@linutronix.de, cmetcalf@ezchip.com, fweisbec@gmail.com, cl@linux.com, h-shimamoto@ct.jp.nec.com, torvalds@linux-foundation.org Reply-To: hpa@zytor.com, peterz@infradead.org, lcapitulino@redhat.com, paulmck@linux.vnet.ibm.com, efault@gmx.de, linux-kernel@vger.kernel.org, cl@linux.com, cmetcalf@ezchip.com, fweisbec@gmail.com, mingo@kernel.org, tglx@linutronix.de, riel@redhat.com, torvalds@linux-foundation.org, h-shimamoto@ct.jp.nec.com In-Reply-To: <1447948054-28668-5-git-send-email-fweisbec@gmail.com> References: <1447948054-28668-5-git-send-email-fweisbec@gmail.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] sched/cputime: Correctly handle task guest time on housekeepers Git-Commit-ID: cab245d68c38afff1a4c4d018ab7e1d316982f5d X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2487 Lines: 59 Commit-ID: cab245d68c38afff1a4c4d018ab7e1d316982f5d Gitweb: http://git.kernel.org/tip/cab245d68c38afff1a4c4d018ab7e1d316982f5d Author: Frederic Weisbecker AuthorDate: Thu, 19 Nov 2015 16:47:31 +0100 Committer: Ingo Molnar CommitDate: Fri, 4 Dec 2015 10:34:44 +0100 sched/cputime: Correctly handle task guest time on housekeepers When a task runs on a housekeeper (a CPU running with the periodic tick with neighbours running tickless), it doesn't account cputime using vtime but relies on the tick. Such a task has its vtime_snap_whence value set to VTIME_INACTIVE. Readers won't handle that correctly though. As long as vtime is running on some CPU, readers incorretly assume that vtime runs on all CPUs and always compute the tickless cputime delta, which is only junk on housekeepers. So lets fix this with checking that the target runs on a vtime CPU through the appropriate state check before computing the tickless delta. Signed-off-by: Frederic Weisbecker Signed-off-by: Peter Zijlstra (Intel) Cc: Chris Metcalf Cc: Christoph Lameter Cc: Hiroshi Shimamoto Cc: Linus Torvalds Cc: Luiz Capitulino Cc: Mike Galbraith Cc: Paul E . McKenney Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Rik van Riel Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1447948054-28668-5-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar --- kernel/sched/cputime.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index 4a18a6e..5cf24e7 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -795,7 +795,7 @@ cputime_t task_gtime(struct task_struct *t) seq = read_seqbegin(&t->vtime_seqlock); gtime = t->gtime; - if (t->flags & PF_VCPU) + if (t->vtime_snap_whence == VTIME_SYS && t->flags & PF_VCPU) gtime += vtime_delta(t); } while (read_seqretry(&t->vtime_seqlock, seq)); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/