Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753378AbbDBSHu (ORCPT ); Thu, 2 Apr 2015 14:07:50 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42419 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753062AbbDBSHr (ORCPT ); Thu, 2 Apr 2015 14:07:47 -0400 Message-ID: <551D852C.90000@redhat.com> Date: Thu, 02 Apr 2015 14:06:36 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: Frederic Weisbecker , LKML CC: Peter Zijlstra , Dave Jones , Thomas Gleixner , Oleg Nesterov , "Paul E . McKenney" , Ingo Molnar Subject: Re: [PATCH 2/3] context_tracking: Inherit TIF_NOHZ through forks instead of context switches References: <1427996365-12101-1-git-send-email-fweisbec@gmail.com> <1427996365-12101-3-git-send-email-fweisbec@gmail.com> In-Reply-To: <1427996365-12101-3-git-send-email-fweisbec@gmail.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1234 Lines: 29 On 04/02/2015 01:39 PM, Frederic Weisbecker wrote: > TIF_NOHZ is used by context_tracking to force syscall slow-path on every > task in order to track userspace roundtrips. As such, it must be set on > all running tasks. > > It's currently explicitly inherited through context switches. There is > no need to do it on this fast-path though. The flag could be simply > set once for all on all tasks, whether they are running or not. > > Lets do this by setting the flag to init task on early boot and let it > propagate through fork inheritance. > > Suggested-by: Oleg Nesterov > Signed-off-by: Frederic Weisbecker > Cc: Thomas Gleixner > Cc: Peter Zijlstra > Cc: Rik van Riel > Cc: Paul E. McKenney > Cc: Ingo Molnar > Cc: Dave Jones > Cc: Oleg Nesterov Reviewed-by: Rik van Riel -- 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/