Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751471AbbFNJTc (ORCPT ); Sun, 14 Jun 2015 05:19:32 -0400 Received: from e38.co.us.ibm.com ([32.97.110.159]:60678 "EHLO e38.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750745AbbFNJTZ (ORCPT ); Sun, 14 Jun 2015 05:19:25 -0400 X-Helo: d03dlp03.boulder.ibm.com X-MailFrom: preeti@linux.vnet.ibm.com X-RcptTo: linux-kernel@vger.kernel.org Message-ID: <557D4714.1090600@linux.vnet.ibm.com> Date: Sun, 14 Jun 2015 14:49:16 +0530 From: Preeti U Murthy User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Frederic Weisbecker , LKML CC: Peter Zijlstra , Thomas Gleixner , Christoph Lameter , Ingo Molnar , Viresh Kumar , Rik van Riel Subject: Re: [PATCH 5/8] nohz: Restart the tick from irq exit References: <1434044168-23173-1-git-send-email-fweisbec@gmail.com> <1434044168-23173-6-git-send-email-fweisbec@gmail.com> In-Reply-To: <1434044168-23173-6-git-send-email-fweisbec@gmail.com> Content-Type: text/plain; charset=ISO-8859-6 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15061409-0029-0000-0000-00000A88DB92 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1090 Lines: 25 On 06/11/2015 11:06 PM, Frederic Weisbecker wrote: > Restart the tick when necessary from the irq exit path. It makes nohz > full more flexible and allow it to piggyback the tick restart on the > scheduler IPI in the future instead of sending a dedicated IPI that > often doubles the scheduler IPI on task wakeup. This will require You can piggy back on the scheduler ipi when you add a timer/hrtimer and add a new task to the runqueue of the nohz_full cpus, since we call resched_curr() in these code paths. But what about the calls to kick nohz_full cpus by perf events and posix cpu timers ? These call sites seem to be concerned about specifically waking up nohz_full cpus as far as I can see. IOW there is no scheduling ipi that we can fall back on in these paths. > careful review of resched_curr() callers. > Regards Preeti U Murthy -- 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/