From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754570Ab0EJFxg (ORCPT ); Mon, 10 May 2010 01:53:36 -0400 Received: from hera.kernel.org ([140.211.167.34]:33814 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754602Ab0EJFxe (ORCPT ); Mon, 10 May 2010 01:53:34 -0400 Date: Mon, 10 May 2010 05:52:34 GMT From: tip-bot for Arjan van de Ven Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, a.p.zijlstra@chello.nl, arjan@linux.intel.com, riel@redhat.com, akpm@linux-foundation.org, tglx@linutronix.de, mingo@elte.hu Reply-To: riel@redhat.com, mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, arjan@linux.intel.com, a.p.zijlstra@chello.nl, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <20100509082208.7cb721f0@infradead.org> References: <20100509082208.7cb721f0@infradead.org> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] sched: Add a comment to get_cpu_idle_time_us() Message-ID: Git-Commit-ID: b1f724c3055fa75a31d272222213647547a2d3d4 X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Mon, 10 May 2010 05:52:35 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: b1f724c3055fa75a31d272222213647547a2d3d4 Gitweb: http://git.kernel.org/tip/b1f724c3055fa75a31d272222213647547a2d3d4 Author: Arjan van de Ven AuthorDate: Sun, 9 May 2010 08:22:08 -0700 Committer: Ingo Molnar CommitDate: Sun, 9 May 2010 19:35:25 +0200 sched: Add a comment to get_cpu_idle_time_us() The exported function get_cpu_idle_time_us() has no comment describing it; add a kerneldoc comment Signed-off-by: Arjan van de Ven Signed-off-by: Andrew Morton Reviewed-by: Rik van Riel Acked-by: Peter Zijlstra Cc: davej@redhat.com LKML-Reference: <20100509082208.7cb721f0@infradead.org> Signed-off-by: Ingo Molnar --- kernel/time/tick-sched.c | 14 ++++++++++++++ 1 files changed, 14 insertions(+), 0 deletions(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index f25735a..358822e 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -179,6 +179,20 @@ static ktime_t tick_nohz_start_idle(struct tick_sched *ts) return now; } +/** + * get_cpu_idle_time_us - get the total idle time of a cpu + * @cpu: CPU number to query + * @last_update_time: variable to store update time in + * + * Return the cummulative idle time (since boot) for a given + * CPU, in microseconds. The idle time returned includes + * the iowait time (unlike what "top" and co report). + * + * This time is measured via accounting rather than sampling, + * and is as accurate as ktime_get() is. + * + * This function returns -1 if NOHZ is not enabled. + */ u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time) { struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);