From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751920Ab3LLAQs (ORCPT ); Wed, 11 Dec 2013 19:16:48 -0500 Received: from mail-pb0-f41.google.com ([209.85.160.41]:36553 "EHLO mail-pb0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750922Ab3LLAQr (ORCPT ); Wed, 11 Dec 2013 19:16:47 -0500 Message-ID: <52A90069.4060401@linaro.org> Date: Thu, 12 Dec 2013 08:16:41 +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 , "Paul E. McKenney" CC: Ingo Molnar , "tglx@linutronix.de" , "linux-kernel@vger.kernel.org" , Linaro Kernel , Li Zhong Subject: Re: nohz_full left a periodic tick cpu issue References: <52A845BD.5020801@linaro.org> <20131211152538.GR4208@linux.vnet.ibm.com> <20131211153114.GB7862@localhost.localdomain> In-Reply-To: <20131211153114.GB7862@localhost.localdomain> 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 On 12/11/2013 11:31 PM, Frederic Weisbecker wrote: >> > OK, I'll bite... Why not just use CONFIG_NO_HZ_FULL_SYSIDLE=y with >> > CONFIG_NO_HZ_FULL_SYSIDLE_SMALL set to at least the number of CPUs on >> > your system? The default for CONFIG_NO_HZ_FULL_SYSIDLE_SMALL is eight. >> > This stuff is in mainline, though Frederic's exploitation of it is >> > still in the works. >> > >> > On smaller systems, with Frederic's latest work, this should allow CPU 0 >> > to go idle quickly. >> > >> > What are you needing that this would not provide? > Yeah I think that's what he needs, but we haven't much advertized that feature > yet. I mean there are good reasons, it's not yet working :o) Many thanks for Paul and Frederic's comments! yes, I enabled FULL_SYSIDLE with FULL_SYSIDLE_SMALL=2, but as Frederic said they are not yet working. > > But yeah Alex, I'm working on plugging the full system idle detection (CONFIG_NO_HZ_FULL_SYSIDLE=y) > to shutdown the timekeeping CPUs adaptively. > > I have the patches ready, I'm just polishing a few things, writing changelogs, then I'll send > to LKML with you Cc'ed :) I am very glad to hear this. looking forward to seeing your patch soon. :) -- Thanks Alex