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From: Ingo Molnar <mingo@elte.hu>
To: Peter Zijlstra <peter@programming.kicks-ass.net>,
	Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
	Dhaval Giani <dhaval@linux.vnet.ibm.com>,
	linux-kernel@vger.kernel.org
Subject: Re: Make yield_task_fair more efficient
Date: Thu, 21 Feb 2008 07:04:27 +0100	[thread overview]
Message-ID: <20080221060427.GA9159@elte.hu> (raw)
In-Reply-To: <20080221053321.GA26918@balbir.in.ibm.com>


* Balbir Singh <balbir@linux.vnet.ibm.com> wrote:

> __pick_last_entity() walks the entire tree on O(lgn) time to find the 
> rightmost entry. This patch makes the routine more efficient by 
> reducing the cost of the lookup

hm, i'm not sure we want to do this: we'd be slowing down the fastpath 
of all the other common scheduler functions, for the sake of a rarely 
used (and broken ...) API: yield. And note that an rbtree walk is not 
slow at all - if you are yielding frequently it's probably all cached.

	Ingo

  reply	other threads:[~2008-02-21  6:04 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-21  5:33 Make yield_task_fair more efficient Balbir Singh
2008-02-21  6:04 ` Ingo Molnar [this message]
2008-02-21  6:51   ` Balbir Singh
2008-02-21  7:07     ` Ingo Molnar
2008-02-21  7:39       ` Balbir Singh
2008-02-21  8:43         ` Peter Zijlstra
2008-02-21  8:50           ` Balbir Singh
2008-02-21  9:04             ` Ingo Molnar
2008-02-21  9:31               ` Balbir Singh
2008-02-21  9:42                 ` Ingo Molnar
2008-02-21  9:44                   ` Balbir Singh
2008-02-21  9:43                 ` Peter Zijlstra
2008-02-21  9:42                   ` Balbir Singh
2008-02-21 10:01                     ` Peter Zijlstra
2008-02-21 10:07                       ` Balbir Singh
2008-02-21 11:12                         ` Peter Zijlstra
2008-02-21 11:27                           ` Balbir Singh
2008-02-21 20:38                           ` Jens Axboe
2008-02-21 20:55                             ` Jens Axboe
2008-02-22  3:27                               ` Balbir Singh
2008-02-21 10:17                 ` Balbir Singh
2008-02-21 12:02                 ` Mike Galbraith
2008-02-21 12:06                   ` Mike Galbraith
2008-02-21 13:29                   ` Balbir Singh
2008-02-21 14:38     ` Jörn Engel

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