From: Ingo Molnar <mingo@elte.hu>
To: Zachary Amsden <zach@vmware.com>
Cc: Glauber de Oliveira Costa <gcosta@redhat.com>,
linux-kernel@vger.kernel.org, tglx@linutronix.de,
rusty@rustcorp.com.au, jeremy@goop.org, --cc@redhat.com,
avi@quramnet.com, kvm-devel@lists.sourceforge.net,
Glauber de Oliveira Costa <glauber@t60.localdomain>,
Dan Hecht <dhecht@vmware.com>, Garrett Smith <garrett@vmware.com>
Subject: Re: [PATCH] raise tsc clocksource rating
Date: Mon, 29 Oct 2007 23:48:52 +0100 [thread overview]
Message-ID: <20071029224852.GA27547@elte.hu> (raw)
In-Reply-To: <1193697734.9793.86.camel@bodhitayantram.eng.vmware.com>
* Zachary Amsden <zach@vmware.com> wrote:
> On Mon, 2007-10-29 at 20:10 -0300, Glauber de Oliveira Costa wrote:
> > From: Glauber de Oliveira Costa <glauber@t60.localdomain>
> >
> > tsc is very good time source (when it does not have drifts, does not
> > change it's frequency, i.e. when it works), so it should have its rating
> > raised to a value greater than, or equal 400.
> >
> > Since it's being a tendency among paravirt clocksources to use values
> > around 400, we should declare tsc as even better: So we use 500.
>
> Why is the TSC better than a paravirt clocksource? In our case this
> is definitely inaccurate. Paravirt clocksources should be preferred
> to TSC, and both must be made available in hardware for platforms
> which do not support paravirt.
if it's inaccurate why are you exposing it to the guest then? Native
only uses the TSC if it's safe and accurate to do so.
Ingo
next prev parent reply other threads:[~2007-10-29 22:48 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-29 23:10 [PATCH] raise tsc clocksource rating Glauber de Oliveira Costa
[not found] ` <11936994092607-git-send-email-gcosta-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2007-10-29 22:17 ` Thomas Gleixner
2007-10-29 22:36 ` Ingo Molnar
2007-10-30 1:26 ` john stultz
[not found] ` <alpine.LFD.0.9999.0710292315280.3186-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2007-10-30 2:39 ` Rusty Russell
[not found] ` <200710301339.23628.rusty-8n+1lVoiYb80n/F98K4Iww@public.gmane.org>
2007-10-30 7:37 ` Ingo Molnar
[not found] ` <20071030073736.GA21843-X9Un+BFzKDI@public.gmane.org>
2007-10-30 10:52 ` Rusty Russell
2007-10-30 12:13 ` Glauber de Oliveira Costa
2007-10-29 22:42 ` Zachary Amsden
[not found] ` <1193697734.9793.86.camel-cxY/u30q8FloTgUnLF1by8fTvwmfpRNyZeezCHUQhQ4@public.gmane.org>
2007-10-29 22:45 ` Jeremy Fitzhardinge
2007-10-29 22:48 ` Ingo Molnar [this message]
[not found] ` <20071029224852.GA27547-X9Un+BFzKDI@public.gmane.org>
2007-10-29 22:52 ` Jeremy Fitzhardinge
2007-10-29 22:55 ` Ingo Molnar
[not found] ` <20071029225528.GA31293-X9Un+BFzKDI@public.gmane.org>
2007-10-29 23:17 ` Jeremy Fitzhardinge
[not found] ` <47266A00.4040408-TSDbQ3PG+2Y@public.gmane.org>
2007-10-29 23:21 ` Ingo Molnar
[not found] ` <20071029232140.GA10518-X9Un+BFzKDI@public.gmane.org>
2007-10-29 23:33 ` Jeremy Fitzhardinge
2007-10-30 0:45 ` Ian Pratt
[not found] ` <8A87A9A84C201449A0C56B728ACF491E34C5F5-sZfJFUT1i4lUWNNKjvdVWtlxNDNUtst69dF7HbQ/qKg@public.gmane.org>
2007-10-30 7:19 ` Ingo Molnar
2007-10-29 22:55 ` Zachary Amsden
2007-10-29 23:02 ` Ingo Molnar
2007-10-29 23:13 ` Zachary Amsden
[not found] ` <1193699638.9793.97.camel-cxY/u30q8FloTgUnLF1by8fTvwmfpRNyZeezCHUQhQ4@public.gmane.org>
2007-10-29 23:17 ` Ingo Molnar
2007-10-30 12:02 ` Glauber de Oliveira Costa
[not found] ` <47271D4A.8030707-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2007-10-30 17:58 ` Zachary Amsden
[not found] ` <20071029230213.GA1982-X9Un+BFzKDI@public.gmane.org>
2007-10-29 23:24 ` Dan Hecht
[not found] ` <47266B90.8000008-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>
2007-10-30 4:24 ` Avi Kivity
2007-10-30 7:14 ` Ingo Molnar
[not found] ` <1193698505.9793.90.camel-cxY/u30q8FloTgUnLF1by8fTvwmfpRNyZeezCHUQhQ4@public.gmane.org>
2007-10-30 11:59 ` Glauber de Oliveira Costa
2007-10-30 0:17 ` H. Peter Anvin
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