linux-kernel - Re: [PATCH]sched_rt.c: Avoid unnecessary dequeue and enqueue of pushable tasks in set_cpus_allowed

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Message-Id: <654301331942324@web109.yandex.ru>
Date:	Sat, 17 Mar 2012 03:58:44 +0400
From:	Kirill Tkhai <tkhai@...dex.ru>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH]sched_rt.c: Avoid unnecessary dequeue and enqueue of pushable tasks in set_cpus_allowed_rt()

Steven, what is about the patch from my previous message? Is everything ok?

Regards,
Kirill

19.02.2012, 18:17, "Kirill Tkhai" <tkhai@...dex.ru>:
> 13.02.2012, 21:23, "Steven Rostedt" <rostedt@...dmis.org>:
>
>>  I wasn't on the Cc of the original message, but it was bounced to me
>>  awhile ago. I'm cleaning out my email and came across it.
>>
>>  Can you send me the latest version of this patch, either against latest
>>  Linus, or against tip/master.
>>
>>  Thanks,
>>
>>  -- Steve
>>
>>  P.S. I'll be at ELC this week so it may not get processed right away.
>
> Migration status depends on a difference of weight from 0 and 1.
> If weight > 1 (<= 1) and old weight <= 1 (> 1) then task becomes
> pushable (or not pushable). We are not insterested in its exact
> values, is it 3 or 4, for example.
>
> Now if we are changing affinity from a set of 3 cpus to a set of 4, the-
> task will be dequeued and enqueued sequentially without important
> difference in comparison with initial state. The only difference is in
> internal representation of plist queue of pushable tasks and the fact
> that the task may won't be the first in a sequence of the same priority
> tasks. But it seems to me it gives nothing.
>
> Signed-off-by: Tkhai Kirill <tkhai@...dex.ru>
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