linux-kernel - Re: [PATCH 0/7] CPU controller

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Date:	Mon, 21 Aug 2006 18:18:30 +0530
From:	Srivatsa Vaddagiri <vatsa@...ibm.com>
To:	Mike Galbraith <efault@....de>
Cc:	Ingo Molnar <mingo@...e.hu>, Nick Piggin <nickpiggin@...oo.com.au>,
	Sam Vilain <sam@...ain.net>, linux-kernel@...r.kernel.org,
	Kirill Korotaev <dev@...nvz.org>,
	Balbir Singh <balbir@...ibm.com>, sekharan@...ibm.com,
	Andrew Morton <akpm@...l.org>, nagar@...son.ibm.com,
	matthltc@...ibm.com, dipankar@...ibm.com
Subject: Re: [PATCH 0/7] CPU controller - V1

On Mon, Aug 21, 2006 at 10:42:40AM +0000, Mike Galbraith wrote:
> WRT interactivity: Looking at try_to_wake_up(), it appears that wake-up
> of a high priority group-a task will not result in preemption of a lower
> priority current group-b task.  True?

I dont think it is true. The definition of TASK_PREEMPTS_CURR() is
unchanged with these patches. Also group priority is linked to the
highest priority task it has. As a result, the high-priority group-a
task should preempt the low priority group-b task.

This is unless group-a has currently run out of its bandwidth and is sitting in 
the expired queue (which is something that the TASK_PREEMPTS_CURR()
can be optimized to check for).

-- 
Regards,
vatsa
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