Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161046AbbKSPvJ (ORCPT ); Thu, 19 Nov 2015 10:51:09 -0500 Received: from mail-wm0-f54.google.com ([74.125.82.54]:35042 "EHLO mail-wm0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758807AbbKSPro (ORCPT ); Thu, 19 Nov 2015 10:47:44 -0500 From: Frederic Weisbecker To: LKML Cc: Hiroshi Shimamoto , Peter Zijlstra , Chris Metcalf , Thomas Gleixner , Luiz Capitulino , Christoph Lameter , "Paul E . McKenney" , Frederic Weisbecker , Ingo Molnar , stable@vger.kernel.org, Rik van Riel Subject: [PATCH 2/7] cputime: Remove extra cost in task_cputime Date: Thu, 19 Nov 2015 16:47:29 +0100 Message-Id: <1447948054-28668-3-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 2.5.3 In-Reply-To: <1447948054-28668-1-git-send-email-fweisbec@gmail.com> References: <1447948054-28668-1-git-send-email-fweisbec@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2267 Lines: 70 From: Hiroshi Shimamoto There is an extra cost in task_cputime() and task_cputime_scaled() when nohz_full is not activated. When vtime accounting is not enabled, we don't need to get deltas of utime and stime under vtime seqlock. This patch removes that cost with adding a shortcut route if vtime accounting is not enabled. Use context_tracking_is_enabled() to check if vtime is accounting on some cpu, in which case only we need to check the tickless cputime delta. Signed-off-by: Hiroshi Shimamoto Cc: stable@vger.kernel.org Cc: Christoph Lameter Cc: Chris Metcalf Cc: Ingo Molnar Cc: Luiz Capitulino Cc: Peter Zijlstra Cc: Rik van Riel Cc: Thomas Gleixner Cc: Paul E. McKenney Cc: Hiroshi Shimamoto Signed-off-by: Frederic Weisbecker --- kernel/sched/cputime.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index 05de80b..1128d4b 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -853,6 +853,14 @@ void task_cputime(struct task_struct *t, cputime_t *utime, cputime_t *stime) { cputime_t udelta, sdelta; + if (!context_tracking_is_enabled()) { + if (utime) + *utime = t->utime; + if (stime) + *stime = t->stime; + return; + } + fetch_task_cputime(t, utime, stime, &t->utime, &t->stime, &udelta, &sdelta); if (utime) @@ -866,6 +874,14 @@ void task_cputime_scaled(struct task_struct *t, { cputime_t udelta, sdelta; + if (!context_tracking_is_enabled()) { + if (utimescaled) + *utimescaled = t->utimescaled; + if (stimescaled) + *stimescaled = t->stimescaled; + return; + } + fetch_task_cputime(t, utimescaled, stimescaled, &t->utimescaled, &t->stimescaled, &udelta, &sdelta); if (utimescaled) -- 2.5.3 -- 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/