Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751415AbaG3IFJ (ORCPT ); Wed, 30 Jul 2014 04:05:09 -0400 Received: from relay.parallels.com ([195.214.232.42]:49831 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751057AbaG3IFC (ORCPT ); Wed, 30 Jul 2014 04:05:02 -0400 Message-ID: <1406707485.3600.32.camel@tkhai> Subject: Re: [PATCH v2 2/5] sched: Teach scheduler to understand ONRQ_MIGRATING state From: Kirill Tkhai To: Oleg Nesterov CC: Peter Zijlstra , Kirill Tkhai , , , , , , , Date: Wed, 30 Jul 2014 12:04:45 +0400 In-Reply-To: <20140729161928.GA31298@redhat.com> References: <20140726145508.6308.69121.stgit@localhost> <20140726145912.6308.32554.stgit@localhost> <20140728080122.GL6758@twins.programming.kicks-ass.net> <1406538338.23175.12.camel@tkhai> <1406627582.3600.9.camel@tkhai> <20140729161928.GA31298@redhat.com> Organization: Parallels Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.8.5-2+b3 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Originating-IP: [10.30.26.172] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org В Вт, 29/07/2014 в 18:19 +0200, Oleg Nesterov пишет: > On 07/29, Kirill Tkhai wrote: > > > > How about this? Everything is inside task_rq_lock() now. The patch > > became much less. > > And with this change task_migrating() is not possible under > task_rq_lock() or __task_rq_lock(). This means that 1/5 can be simplified > too. It seems to me it won't be useless anyway. In every place we underline that a task is exactly queued or dequeued, so it's not necessary to remember whether it is migrating or not. This is a cleanup, though it's big. > __migrate_swap_task() is probably the notable exception... > > Off-topic, but it takes 2 ->pi_lock's. This means it can deadlock with > try_to_wake_up_local() (if a 3rd process does ttwu() and waits for > ->on_cpu == 0). But I guess __migrate_swap_task() should not play with > PF_WQ_WORKER threads. Hmm.. I'm surprised, PF_WQ_WORKER threads may be unbound. But it seems we still can't pass them to try_to_wake_up_local. Regards, Kirill -- 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/