From: Ingo Molnar <mingo@elte.hu>
To: Martin Roehricht <ml@felicis.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Scheduling the highest priority task
Date: Thu, 2 Aug 2007 17:03:50 +0200 [thread overview]
Message-ID: <20070802150350.GA3030@elte.hu> (raw)
In-Reply-To: <46B1F182.3010608@felicis.org>
* Martin Roehricht <ml@felicis.org> wrote:
> On 08/02/2007 01:40 PM, Ingo Molnar wrote:
> >in the SMP migration code, the 'old scheduler' indeed picks the lowest
> >priority one, _except_ if that task is running on another CPU or is too
> >'cache hot':
>
> But why is it, that the scheduler picks the lowest priority one? I
> thought sched_find_first_bit() picks the index of the lowest order bit
> in the bitmap and thus the highest priority job. Is that wrong? What
> needs to be changed to let the scheduler pick the highest priority
> task from a given runqueue? I am very confused ...
it first picks the lowest index (i.e. the highest priority active
priority-queue), but within those tasks (each task in that priority
queue has equal priority) the load-balancer has freedom to pick any.
Based on performance data we went for picking from the tail of the
queue.
Ingo
next prev parent reply other threads:[~2007-08-02 15:04 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <8KLFD-G9-5@gated-at.bofh.it>
2007-07-25 15:18 ` highest and lowest priority job of a runqueue Martin Roehricht
2007-08-02 8:58 ` Scheduling the highest priority task Martin Roehricht
2007-08-02 11:40 ` Ingo Molnar
2007-08-02 15:00 ` Martin Roehricht
2007-08-02 15:03 ` Ingo Molnar [this message]
2007-08-02 15:14 ` Martin Roehricht
2007-08-02 15:19 ` Ingo Molnar
2007-08-02 15:46 ` Martin Roehricht
2007-08-02 19:48 ` Ingo Molnar
2007-08-02 21:05 ` Martin Roehricht
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