Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751996AbbEZRsm (ORCPT ); Tue, 26 May 2015 13:48:42 -0400 Received: from mail-ig0-f174.google.com ([209.85.213.174]:38360 "EHLO mail-ig0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751941AbbEZRsj (ORCPT ); Tue, 26 May 2015 13:48:39 -0400 From: bsegall@google.com To: Kirill Tkhai Cc: , Peter Zijlstra , Konstantin Khlebnikov , Mohammed Naser , "Ingo Molnar" , Kirill Tkhai Subject: Re: [PATCH 2/2] sched: Update runtime of prev task before doing pick_next_task() References: <20150526114344.14783.90095.stgit@pro> <1432641008.6866.59.camel@odin.com> Date: Tue, 26 May 2015 10:48:36 -0700 In-Reply-To: <1432641008.6866.59.camel@odin.com> (Kirill Tkhai's message of "Tue, 26 May 2015 14:50:08 +0300") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1307 Lines: 29 Kirill Tkhai writes: > pick_next_task() puts prev rq's task. This may lead to runtime > expiration and to dequeueing of all scheduling class's tasks > because of throttling. And the current logic is that put_prev_task() > must be called in the pick method of next task's class. > > This was fixed for RT and DL classes, while fair class have this > problem. So, instead of doing partial solutions, let's update prev > task's runtime for all classes in __schedule() and fix the problem > completelly. > > Also, let's freeze the clock during pick_next_task() to be sure > new expirations of runtime won't happen. > > Reported-by: Konstantin Khlebnikov > Reported-by: Mohammed Naser > Signed-off-by: Kirill Tkhai If this is actually the bug I sent a patch for (and that I was correct in guessing what the issue /was/, which is not at all certain), this won't actually eliminate the issue - I couldn't find a race involving actual updates but did find one with disable/enable. -- 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/