linux-kernel - Re: [PATCH] raise tsc clocksource rating

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Message-ID: <47267832.1060003@zytor.com>
Date:	Mon, 29 Oct 2007 17:17:54 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Glauber de Oliveira Costa <gcosta@...hat.com>
CC:	linux-kernel@...r.kernel.org, tglx@...utronix.de,
	rusty@...tcorp.com.au, jeremy@...p.org, --cc@...hat.com,
	mingo@...e.hu, avi@...amnet.com, kvm-devel@...ts.sourceforge.net,
	Glauber de Oliveira Costa <glauber@....localdomain>
Subject: Re: [PATCH] raise tsc clocksource rating

Glauber de Oliveira Costa wrote:
> From: Glauber de Oliveira Costa <glauber@....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.
> 
> This patch also touches the comments on clocksource.h, which suggests
> that 499 would be a limit on the rating values.
> 
> Signed-off-by: Glauber de Oliveira Costa <gcosta@...hat.com>

Are you sure these paravirt sources don't intentionally trump the TSC?

	-hpa

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