Date: Mon, 3 Oct 2005 19:30:32 +0530
From: Dinakar Guniguntala <dino@in.ibm.com>
To: Paul Jackson <pj@sgi.com>
Cc: kurosawa@valinux.co.jp, taka@valinux.co.jp, magnus.damm@gmail.com,
       linux-kernel@vger.kernel.org, ckrm-tech@lists.sourceforge.net
Subject: Re: Ok to change cpuset flags for sched domains? (was [PATCH 1/3] CPUMETER ...)
Message-ID: <20051003140032.GA6629@in.ibm.com>
Reply-To: dino@in.ibm.com
References: <20050908225539.0bc1acf6.pj@sgi.com> <20050909.203849.33293224.taka@valinux.co.jp> <20050909063131.64dc8155.pj@sgi.com> <20050910.161145.74742186.taka@valinux.co.jp> <20050910015209.4f581b8a.pj@sgi.com> <20050926093432.9975870043@sv1.valinux.co.jp> <20050927013751.47cbac8b.pj@sgi.com> <20050927113902.C78A570046@sv1.valinux.co.jp> <20050927084905.7d77bdde.pj@sgi.com> <20051002000159.3f15bf7a.pj@sgi.com>
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I have been wanting to follow the cpumeter discussion more closely,
but currently am tied up. I hope to have more time towards the end of
this week.

I had a few queries below, though

On Sun, Oct 02, 2005 at 12:01:59AM -0700, Paul Jackson wrote:
> Dinikar,
> 
> How much grief will it cause you if I make the following incompatible
> change to the special boolean files in each cpuset directory?
> 
> I think I goofed in encouraging you to overload "cpu_exclusive"
> with defining dynamic scheduler domains.  I should have asked for a
> separate flag to be added for that, say "sched_domain", which would
> require "cpu_exclusive=1" as a precondition.  Other attributes that
> require cpu_exclusive or mem_exclusive are showing up, and it makes
> more sense for each of them to get their own boolean, and leave the
> "*_exclusive" flags to specify just the exclusive (no overlap with
> sibling) attribute.


One of the reasons for overloading the cpu_exclusive flag was to
ensure that the rebalance code does not try to pull tasks unnecessarily

With the scheme that you are proposing that is a possibility if
you turn on the cpu_exclusive and meter_cpu for example and not
turn on sched_domain. Is there a reason why we would want to have
exclusive cpusets not attached to sched domains at all?

I am not entirely convinced that we can compare sched_domains and 
meter_cpus.

However I am still open if there is a convincing reason to have
exclusive cpusets that dont form sched domains.

	-Dinakar
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