From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755264AbaHFIGJ (ORCPT ); Wed, 6 Aug 2014 04:06:09 -0400 Received: from relay.parallels.com ([195.214.232.42]:51356 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755200AbaHFIGE (ORCPT ); Wed, 6 Aug 2014 04:06:04 -0400 Message-ID: <1407312354.8424.34.camel@tkhai> Subject: [PATCH v4 0/6] sched: Add on_rq states and remove several double rq locks From: Kirill Tkhai To: CC: , , , , , , , , Date: Wed, 6 Aug 2014 12:05:54 +0400 Organization: Parallels Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.8.5-2+b3 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Originating-IP: [10.30.26.172] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This series aims to get rid of some places where locks of two RQs are held at the same time. Patch [1/6] is a fix/preparation. It's new in v4 version of series. Patch [2/6] is a preparation/cleanup. It replaces old (task_struct::on_rq == 1) with new (task_struct::on_rq == ONRQ_QUEUED) everywhere. No functional changes. Patch [3/6] is main in the series. It introduces new ONRQ_MIGRATING state and teaches scheduler to understand it (we need little changes in try_to_wake_up() and task_rq_lock() family). This will be used in the following way: (we are changing task's rq) raw_spin_lock(&src_rq->lock); p = ...; /* Some src_rq task */ dequeue_task(src_rq, p, 0); p->on_rq = ONRQ_MIGRATING; set_task_cpu(p, dst_cpu); raw_spin_unlock(&src_rq->lock); /* * Now p is dequeued, and both * RQ locks are unlocked, but * its on_rq is not zero. * Nobody can manipulate p * while it's migrating, * even when spinlocks are * unlocked. */ raw_spin_lock(&dst_rq->lock); p->on_rq = ONRQ_QUEUED; enqueue_task(dst_rq, p, 0); raw_spin_unlock(&dst_rq->lock); Patches [4,5,6/6] remove double locks and use new ONRQ_MIGRATING state. They allow unlocked using of 3-4 function, which looks safe for me. The profit is double_rq_lock() is not need now, so we reduce the total time when RQs are locked. --- v4: New patch [1/6] Kirill Tkhai (6): sched/fair: Fix reschedule which is generated on throttled cfs_rq sched: Wrapper for checking task_struct::on_rq sched: Teach scheduler to understand ONRQ_MIGRATING state sched: Remove double_rq_lock() from __migrate_task() sched/fair: Remove double_lock_balance() from active_load_balance_cpu_stop() sched/fair: Remove double_lock_balance() from load_balance() kernel/sched/core.c | 115 +++++++++++++++++------------- kernel/sched/deadline.c | 14 ++-- kernel/sched/fair.c | 174 +++++++++++++++++++++++++++++++--------------- kernel/sched/rt.c | 16 ++-- kernel/sched/sched.h | 13 +++ kernel/sched/stop_task.c | 2 - 6 files changed, 212 insertions(+), 122 deletions(-) -- Signed-off-by: Kirill Tkhai