From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: frank.rowand@am.sony.com
Cc: Chris Mason <chris.mason@oracle.com>,
"Rowand, Frank" <Frank_Rowand@sonyusa.com>,
Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
Mike Galbraith <efault@gmx.de>, Oleg Nesterov <oleg@redhat.com>,
Paul Turner <pjt@google.com>, Jens Axboe <axboe@kernel.dk>,
Yong Zhang <yong.zhang0@gmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 22/22] sched: Remove TASK_WAKING
Date: Wed, 16 Mar 2011 10:53:20 +0100 [thread overview]
Message-ID: <1300269200.2250.83.camel@laptop> (raw)
In-Reply-To: <4D797F92.6020504@am.sony.com>
On Thu, 2011-03-10 at 17:49 -0800, Frank Rowand wrote:
> On 03/02/11 09:38, Peter Zijlstra wrote:
> > With the new locking TASK_WAKING has become obsolete, remove it.
> >
> > Suggested-by: Oleg Nesterov <oleg@redhat.com>
> > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> > LKML-Reference: <new-submission>
> > ---
>
> < snip >
>
> > Index: linux-2.6/kernel/sched.c
> > ===================================================================
> > --- linux-2.6.orig/kernel/sched.c
> > +++ linux-2.6/kernel/sched.c
> > @@ -2175,7 +2175,7 @@ void set_task_cpu(struct task_struct *p,
> > * We should never call set_task_cpu() on a blocked task,
> > * ttwu() will sort out the placement.
> > */
> > - WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
> > + WARN_ON_ONCE(p->state != TASK_RUNNING &&
> > !(task_thread_info(p)->preempt_count & PREEMPT_ACTIVE));
> >
> > #ifdef CONFIG_LOCKDEP
> > @@ -2613,7 +2613,7 @@ try_to_wake_up(struct task_struct *p, un
> > smp_rmb();
> >
> > p->sched_contributes_to_load = !!task_contributes_to_load(p);
> > - p->state = TASK_WAKING;
> > + p->state = TASK_RUNNING;
> >
> > if (p->sched_class->task_waking)
> > p->sched_class->task_waking(p);
>
> No harm if the coded as in the patch, but an alternate suggestion
> if you like it:
>
> The only reason left for "p->state = TASK_RUNNING;" here is when
> cpu is remote. If cpu is not remote then p->state will be set by:
>
> ttwu_queue()
> ttwu_do_activate()
> ttwu_do_wakeup()
> p->state = TASK_RUNNING;
>
> It would be more clear that setting state to TASK_RUNNING is protecting
> the process until it has been removed from the wake_list by
> sched_ttwu_pending() by setting p->state = TASK_RUNNING in ttwu_queue_remote().
>
Yeah, its a bit of a maze.. maybe we should just drop this and keep the
slightly redundant but more clear TASK_WAKING around.
next prev parent reply other threads:[~2011-03-16 9:51 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-02 17:38 [PATCH 00/22] sched: Reduce runqueue lock contention -v5 Peter Zijlstra
2011-03-02 17:38 ` [PATCH 01/22] sched: Provide scheduler_ipi() callback in response to smp_send_reschedule() Peter Zijlstra
2011-03-11 1:36 ` Frank Rowand
2011-03-16 8:30 ` Peter Zijlstra
2011-03-11 15:07 ` [01/22] " Milton Miller
2011-03-11 15:27 ` Peter Zijlstra
2011-03-15 3:59 ` Milton Miller
2011-03-15 9:13 ` Peter Zijlstra
2011-03-02 17:38 ` [PATCH 02/22] sched: Always provide p->on_cpu Peter Zijlstra
2011-03-02 17:38 ` [PATCH 03/22] mutex: Use p->on_cpu for the adaptive spin Peter Zijlstra
2011-03-02 17:38 ` [PATCH 04/22] sched: Change the ttwu success details Peter Zijlstra
2011-03-02 17:38 ` [PATCH 05/22] sched: Clean up ttwu stats Peter Zijlstra
2011-03-02 17:38 ` [PATCH 06/22] sched: Provide p->on_rq Peter Zijlstra
2011-03-02 17:38 ` [PATCH 07/22] sched: Serialize p->cpus_allowed and ttwu() using p->pi_lock Peter Zijlstra
2011-03-02 17:38 ` [PATCH 08/22] sched: Drop the rq argument to sched_class::select_task_rq() Peter Zijlstra
2011-03-02 17:38 ` [PATCH 09/22] sched: Remove rq argument to sched_class::task_waking() Peter Zijlstra
2011-03-02 17:38 ` [PATCH 10/22] sched: Deal with non-atomic min_vruntime reads on 32bits Peter Zijlstra
2011-03-02 17:38 ` [PATCH 11/22] sched: Delay task_contributes_to_load() Peter Zijlstra
2011-03-02 17:38 ` [PATCH 12/22] sched: Also serialize ttwu_local() with p->pi_lock Peter Zijlstra
2011-03-02 17:38 ` [PATCH 13/22] sched: Add p->pi_lock to task_rq_lock() Peter Zijlstra
2011-03-02 17:38 ` [PATCH 14/22] sched: Drop rq->lock from first part of wake_up_new_task() Peter Zijlstra
2011-03-02 17:38 ` [PATCH 15/22] sched: Drop rq->lock from sched_exec() Peter Zijlstra
2011-03-02 17:38 ` [PATCH 16/22] sched: Remove rq->lock from the first half of ttwu() Peter Zijlstra
2011-03-02 17:38 ` [PATCH 17/22] sched: Remove rq argument from ttwu_stat() Peter Zijlstra
2011-03-02 17:38 ` [PATCH 18/22] sched: Rename ttwu_post_activation Peter Zijlstra
2011-03-02 17:38 ` [PATCH 19/22] sched: Restructure ttwu some more Peter Zijlstra
2011-03-02 17:38 ` [PATCH 20/22] sched: Move the second half of ttwu() to the remote cpu Peter Zijlstra
2011-03-11 1:44 ` Frank Rowand
2011-03-16 8:32 ` Peter Zijlstra
2011-03-02 17:38 ` [PATCH 21/22] sched: Remove need_migrate_task() Peter Zijlstra
2011-03-02 17:38 ` [PATCH 22/22] sched: Remove TASK_WAKING Peter Zijlstra
2011-03-11 1:49 ` Frank Rowand
2011-03-16 9:53 ` Peter Zijlstra [this message]
2011-03-11 1:51 ` [PATCH 00/22] sched: Reduce runqueue lock contention -v5 Frank Rowand
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