Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932980AbaDIKdD (ORCPT ); Wed, 9 Apr 2014 06:33:03 -0400 Received: from mail-oa0-f54.google.com ([209.85.219.54]:46593 "EHLO mail-oa0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750784AbaDIKdB (ORCPT ); Wed, 9 Apr 2014 06:33:01 -0400 MIME-Version: 1.0 Date: Wed, 9 Apr 2014 16:03:00 +0530 Message-ID: Subject: [Query]: tick-sched: why don't we stop tick when we are running idle task? From: Viresh Kumar To: =?ISO-8859-1?Q?Fr=E9d=E9ric_Weisbecker?= Cc: Thomas Gleixner , Linux Kernel Mailing List , Lists linaro-kernel Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Frederic, File: kernel/time/tick-sched.c Function: tick_nohz_full_stop_tick() We are doing this: if (!tick_nohz_full_cpu(cpu) || is_idle_task(current)) return; Which means: if a FULL_NO_HZ cpu is running idle task currently, don't stop its tick.. I couldn't understand why. Can you please help here? -- viresh -- 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/