Messages in this thread | | | From | Rusty Russell <> | Subject | Re: [PATCH] raise tsc clocksource rating | Date | Tue, 30 Oct 2007 13:39:23 +1100 |
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On Tuesday 30 October 2007 09:17:38 Thomas Gleixner wrote: > On Mon, 29 Oct 2007, Glauber de Oliveira Costa wrote: > > CC'ed John and removed glauber@t60.localdomain :) > > > 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. > > > > 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@redhat.com> > > Acked-by: Thomas Gleixner <tglx@linutronix.de>
No. tsc is very good, it's not perfect. If a paravirt clock registers 400 it really means "pick me over the tsc".
That's *why* they use > 400: it's in the documentation.
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