linux-kernel - Re: Stolen and degraded time and schedulers

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Message-Id: <1173888673.3101.12.camel@imap.mvista.com>
Date:	Wed, 14 Mar 2007 09:11:13 -0700
From:	Daniel Walker <dwalker@...sta.com>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
Cc:	john stultz <johnstul@...ibm.com>, Andi Kleen <ak@...e.de>,
	Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Con Kolivas <kernel@...ivas.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Zachary Amsden <zach@...are.com>,
	James Morris <jmorris@...ei.org>,
	Chris Wright <chrisw@...s-sol.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	cpufreq@...ts.linux.org.uk,
	Virtualization Mailing List <virtualization@...ts.osdl.org>
Subject: Re: Stolen and degraded time and schedulers

On Tue, 2007-03-13 at 23:52 -0700, Jeremy Fitzhardinge wrote:

> >
> > That's true, but given a constant clock (like what sched_clock should
> > have) then the accounting is similarly inaccurate. Any connection
> > between the scheduler and the TSC frequency changes aren't part of the
> > design AFAIK ..
> >   
> 
> Well, my whole argument is that sched_clock /should not/ be a constant
> clock.  And I'm not quite sure why you keep bringing up the tsc, because
> it has no relevance.

Then your direction is wrong, sched_clock() should be constant ideally
(1millisecond should really be 1millisecond). Like I said in the last
email, change the scheduler to make it aware of the variable quantum
values.

Daniel

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