From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750864Ab3LKG3H (ORCPT ); Wed, 11 Dec 2013 01:29:07 -0500 Received: from mail-pb0-f53.google.com ([209.85.160.53]:40304 "EHLO mail-pb0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750719Ab3LKG3B (ORCPT ); Wed, 11 Dec 2013 01:29:01 -0500 Message-ID: <52A80627.9020109@linaro.org> Date: Wed, 11 Dec 2013 14:28:55 +0800 From: Alex Shi User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: Frederic Weisbecker , Ingo Molnar , "tglx@linutronix.de" , "linux-kernel@vger.kernel.org" , Linaro Kernel Subject: nohz_full left a periodic tick cpu issue Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Frederic, Sorry for idiot of nohz_full. When we using this feature on my mobile devices, we found this feature keep cpu0 in periodic tick mode. then the timer interrupt on cpu0 is very higher than normal nohz mode. that cause high power consuming cost. I found you have mention this on commit: a382bf934449 nohz: Assign timekeeping duty to a CPU outside the full dynticks range In fact, if all full dynticks cpu are in idle, cpu0 should be safe to get into idle too. Do you have some plan or idea to implement this? otherwise, power cost is too high to enable nohz_full in mobile platform. -- Thanks Alex