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Date: Wed, 14 Mar 2007 21:38:26 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Dan Hecht <dhecht@vmware.com>, dwalker@mvista.com,
       cpufreq@lists.linux.org.uk,
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       john stultz <johnstul@us.ibm.com>, Thomas Gleixner <tglx@linutronix.de>,
       paulus@au.ibm.com, schwidefsky@de.ibm.com,
       Rik van Riel <riel@redhat.com>
Subject: Re: Stolen and degraded time and schedulers
Message-ID: <20070314203826.GA15394@elte.hu>
References: <45F6D1D0.6080905@goop.org> <1173816769.22180.14.camel@localhost> <45F70A71.9090205@goop.org> <1173821224.1416.24.camel@dwalker1> <45F71EA5.2090203@goop.org> <45F74515.7010808@vmware.com> <45F77C27.8090604@goop.org> <45F846AB.6060200@vmware.com> <45F84E39.7030507@goop.org>
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* Jeremy Fitzhardinge <jeremy@goop.org> wrote:

> I added stolen time accounting to xen-pv_ops last night.  For Xen, at 
> least, it wasn't hard to fit into the clockevent infrastructure.  I 
> just update the stolen time accounting for each cpu when it gets a 
> timer tick; they seem to get a tick every couple of seconds even when 
> idle.

touching the 'timer tick' is the wrong approach. 'stolen time' only 
matters to the /scheduler tick/. So extend the hypervisor interface to 
allow the injection of 'virtual' scheduler tick events: via the use of a 
special clockevents device - do not change clockevents itself.

	Ingo