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From: Venkatesh Pallipadi <venki@google.com>
To: Rik van Riel <riel@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>,
	a.p.zijlstra@chello.nl, mingo@redhat.com, hpa@zytor.com,
	linux-kernel@vger.kernel.org, mtosatti@redhat.com,
	tglx@linutronix.de, mingo@elte.hu
Subject: Re: [PATCH] sched: resched proper CPU on yield_to
Date: Tue, 1 Mar 2011 19:37:07 -0800	[thread overview]
Message-ID: <AANLkTikL28vknFkp1NBkqQq3wpZK8A-C5WABKiYsqR2o@mail.gmail.com> (raw)
In-Reply-To: <4D6DBA7F.7010203@redhat.com>

On Tue, Mar 1, 2011 at 7:33 PM, Rik van Riel <riel@redhat.com> wrote:
> On 03/01/2011 07:28 PM, Venkatesh Pallipadi wrote:
>>
>> yield_to_task_fair() has code to resched the CPU of yielding task when the
>> intention is to resched the CPU of the task that is being yielded to.
>>
>> Change here fixes the problem and also makes the resched conditional on
>> rq != p_rq.
>
> That would result in not rescheduling when current and p are
> on the same runqueue, in effect making yield_to a noop for the
> easiest case...
>
> When rq != p_rq, we need to ensure both get rescheduled.
>

Yes. There is a schedule() right after this change which should take
care or resched on current CPU. Thats the reason I thought of skipping
resched on current CPU. No?

Thanks,
Venki

> We want to have current not run right now (because it is waiting
> on a resource that's not available), and we do want p to run.
>
> I'm about to fall over, so I'll go to sleep now.
>
> I can send a patch tomorrow morning, unless you beat me to it :)
>
> --
> All rights reversed
>

  reply	other threads:[~2011-03-02  3:37 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-02-01 14:44 [PATCH -v8a 0/7] directed yield for Pause Loop Exiting Rik van Riel
2011-02-01 14:47 ` [PATCH -v8a 1/7] sched: check the right ->nr_running in yield_task_fair Rik van Riel
2011-02-03 14:11   ` [tip:sched/core] sched: Check the right ->nr_running in yield_task_fair() tip-bot for Rik van Riel
2011-02-01 14:48 ` [PATCH -v8a 2/7] sched: limit the scope of clear_buddies Rik van Riel
2011-02-03 14:11   ` [tip:sched/core] sched: Limit " tip-bot for Rik van Riel
2011-02-01 14:50 ` [PATCH -v8a 4/7] sched: Add yield_to(task, preempt) functionality Rik van Riel
2011-02-01 15:52   ` Peter Zijlstra
2011-02-03 12:58   ` Peter Zijlstra
2011-02-03 14:12   ` [tip:sched/core] " tip-bot for Mike Galbraith
2011-02-26  0:43     ` Venkatesh Pallipadi
2011-02-26  5:44       ` Rik van Riel
2011-02-28  9:26         ` Mike Galbraith
2011-03-02  0:28           ` [PATCH] sched: resched proper CPU on yield_to Venkatesh Pallipadi
2011-03-02  3:33             ` Rik van Riel
2011-03-02  3:37               ` Venkatesh Pallipadi [this message]
2011-03-02  3:52             ` Rik van Riel
2011-03-04 11:50             ` [tip:sched/core] sched: Resched proper CPU on yield_to() tip-bot for Venkatesh Pallipadi
2011-02-01 14:51 ` [PATCH -v8a 3/7] sched: use a buddy to implement yield_task_fair Rik van Riel
2011-02-01 15:53   ` Peter Zijlstra
2011-02-03 12:58   ` Peter Zijlstra
2011-02-03 14:12   ` [tip:sched/core] sched: Use a buddy to implement yield_task_fair() tip-bot for Rik van Riel
2011-02-01 14:51 ` [PATCH -v8a 5/7] export pid symbols needed for kvm_vcpu_on_spin Rik van Riel
2011-02-01 14:52 ` [PATCH -v8a 6/7] kvm: keep track of which task is running a KVM vcpu Rik van Riel
2011-02-01 14:53 ` [PATCH -v8a 7/7] kvm: use yield_to instead of sleep in kvm_vcpu_on_spin Rik van Riel
2011-02-07  9:08 ` [PATCH -v8a 0/7] directed yield for Pause Loop Exiting Avi Kivity

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