linux-kernel - Re: [PATCH] sched: next buddy hint on sleep and preempt path

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Message-ID: <4D6DAEF9.6000806@redhat.com>
Date:	Tue, 01 Mar 2011 21:44:09 -0500
From:	Rik van Riel <riel@...hat.com>
To:	Venkatesh Pallipadi <venki@...gle.com>
CC:	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...e.hu>,
	linux-kernel@...r.kernel.org, Paul Turner <pjt@...gle.com>,
	Mike Galbraith <efault@....de>
Subject: Re: [PATCH] sched: next buddy hint on sleep and preempt path

On 03/01/2011 06:33 PM, Venkatesh Pallipadi wrote:
> When a task in a taskgroup sleeps, pick_next_task starts all the way back at
> the root and picks the task/taskgroup with the min vruntime across all
> runnable tasks. But, when there are many frequently sleeping tasks
> across different taskgroups, it makes better sense to stay with same taskgroup
> for its slice period (or until all tasks in the taskgroup sleeps) instead of
> switching cross taskgroup on each sleep after a short runtime.
> This helps specifically where taskgroups corresponds to a process with
> multiple threads. The change reduces the number of CR3 switches in this case.

Nice!

> Signed-off-by: Venkatesh Pallipadi<venki@...gle.com>

Acked-by: Rik van Riel <riel@...hat.com>

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