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From: Ingo Oeser <ioe-lkml@rameria.de>
To: Gregory Haskins <ghaskins@novell.com>
Cc: linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org,
	Steven Rostedt <rostedt@goodmis.org>,
	Dmitry Adamushko <dmitry.adamushko@gmail.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Ingo Molnar <mingo@elte.hu>, Darren Hart <dvhltc@us.ibm.com>
Subject: Re: [PATCH 13/13] RT: Cache cpus_allowed weight for optimizing migration
Date: Wed, 24 Oct 2007 02:19:23 +0200	[thread overview]
Message-ID: <200710240219.25487.ioe-lkml@rameria.de> (raw)
In-Reply-To: <20071023165130.5536.73345.stgit@novell1.haskins.net>

Hi Gregory,

On Tuesday 23 October 2007, Gregory Haskins wrote:
> Calculating the weight is probably relatively expensive, so it is only
> done when the cpus_allowed mask is updated (which should be relatively
> infrequent, especially compared to scheduling frequency) and cached in
> the task_struct.

Why not make it a task flag, since according to your code, you are only 
interested whether this is <= 1 or > 1. Since !(x <= 1) <=> (x > 1)
for any given unsigned integer x, the required data structure is
a "boolean" or a flag.


Best Regards

Ingo Oeser

  reply	other threads:[~2007-10-24  0:23 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-10-23 16:50 [PATCH 00/13] Balance RT tasks v5 Gregory Haskins
2007-10-23 16:50 ` [PATCH 01/13] RT: push-rt Gregory Haskins
2007-10-23 16:50 ` [PATCH 02/13] RT: Condense the next-task search into one function Gregory Haskins
2007-10-23 16:50 ` [PATCH 03/13] RT: Add a per-cpu rt_overload indication Gregory Haskins
2007-10-23 16:50 ` [PATCH 04/13] RT: Wrap the RQ notion of priority to make it conditional Gregory Haskins
2007-10-23 16:50 ` [PATCH 05/13] RT: Initialize the priority value Gregory Haskins
2007-10-23 16:50 ` [PATCH 06/13] RT: Maintain the highest RQ priority Gregory Haskins
2007-10-23 16:50 ` [PATCH 07/13] RT: Clean up some of the push-rt logic Gregory Haskins
2007-10-23 16:51 ` [PATCH 08/13] RT: Add support for low-priority wake-up to push_rt feature Gregory Haskins
2007-10-23 16:51 ` [PATCH 09/13] RT: Only dirty a cacheline if the priority is actually changing Gregory Haskins
2007-10-23 16:51 ` [PATCH 10/13] RT: Fixes for push-rt patch Gregory Haskins
2007-10-23 16:51 ` [PATCH 11/13] RT: Condense NORMAL and IDLE priorities Gregory Haskins
2007-10-23 16:51 ` [PATCH 12/13] RT: CPU priority management Gregory Haskins
2007-10-23 16:51 ` [PATCH 13/13] RT: Cache cpus_allowed weight for optimizing migration Gregory Haskins
2007-10-24  0:19   ` Ingo Oeser [this message]
2007-10-24  3:20     ` Gregory Haskins

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