From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ingo Molnar <mingo@elte.hu>
Subject: Re: Stolen and degraded time and schedulers
Date: Fri, 16 Mar 2007 09:38:28 +0100
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To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: dwalker@mvista.com, john stultz <johnstul@us.ibm.com>, paulus@au.ibm.com, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Con Kolivas <kernel@kolivas.org>, Chris Wright <chrisw@sous-sol.org>, Virtualization Mailing List <virtualization@lists.osdl.org>, cpufreq@lists.linux.org.uk, schwidefsky@de.ibm.com, Thomas Gleixner <tglx@linutronix.de>


* Jeremy Fitzhardinge <jeremy@goop.org> wrote:

> Ingo Molnar wrote:
> > 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.
> =

> I didn't.  I was using sloppy terminology: I hang the stolen time =

> accounting off the Xen timer interrupt routine, just so that it gets =

> run every now and again.

i dont understand: how are you separating 'stolen time' drifts from =

events generated for absolute timeouts?

> I suppose I could explicitly hook stolen time accounting into the =

> scheduler, but its not obvious to me that it's necessary.

right now i dont see any clean way to solve this problem without having =

two clockevents drivers: one for the scheduler, one for timer events.

	Ingo