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RE: [Xen-devel] Xenoprof: getting Oprofile out of timer mode?

To: "Ray Bryant" <raybry@xxxxxxxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] Xenoprof: getting Oprofile out of timer mode?
From: "Santos, Jose Renato G" <joserenato.santos@xxxxxx>
Date: Wed, 24 May 2006 00:02:02 -0700
Cc: Gitika Aggarwal <gitika@xxxxxxxxx>, Andrei Lifchits <alifchit@xxxxxxxxx>
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Thread-topic: [Xen-devel] Xenoprof: getting Oprofile out of timer mode?
According to the Intel manual cpu_model 6 has the same
perf counters as the other models of the p4 family.
Thus, the patch seems the right fix, except
that it would be better to use (cpu_model > 6)
instead of (cpu_model > 7).
Keir is right, oprofile should have the same problem
in native Linux. I guess we could submit a similar 
patch for oprofile to the linux kernel mailing list.


> -----Original Message-----
> From: Ray Bryant [mailto:raybry@xxxxxxxxxxxxxxxxx] 
> Sent: Tuesday, May 23, 2006 3:33 PM
> To: xen-devel@xxxxxxxxxxxxxxxxxxx
> Cc: Santos, Jose Renato G; Gitika Aggarwal; Andrei Lifchits
> Subject: Re: [Xen-devel] Xenoprof: getting Oprofile out of timer mode?
> On Sunday 21 May 2006 01:53, Santos, Jose Renato G wrote:
> > Xenoprof initialization is failing with -ENODEV status (-19).
> > There are two conditions that would cause this:
> > 1) The local APIC is not available (cpu_has_apic is false)
> > 2) OR the cpu (family/model) is not one of the known CPU models
> >    in xenoprof
> >
> > Have you tried running Oprofile in vanila linux?
> > Does OProfile recognize the CPU model and the APIC in Linux?
> >
> > Renato
> >
> Yeah, it looks the problem is the following check in
> arch/x86/oprofile/nmi_int.c:
>       if (cpu_model > 4)
>               return 0;
> Intel processors 920 and 955 (perhaps others, you would have 
> to ask Intel) appear to return 6 as the cpu model.  Making 
> the obvious change to the above 
> gets oprofile out of timer only mode.   An obvious patch is attached.
> --
> Ray Bryant
> AMD Performance Labs                   Austin, Tx
> 512-602-0038 (o)                 512-507-7807 (c)

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