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    SubjectRe: [PATCH 08/11] perf tool: precise mode requires exclude_guest
    On 7/24/12 10:15 AM, Robert Richter wrote:
    > David,
    >
    > On 24.07.12 08:20:19, David Ahern wrote:
    >> On 7/23/12 12:13 PM, Arnaldo Carvalho de Melo wrote:
    >>> Em Fri, Jul 20, 2012 at 05:25:53PM -0600, David Ahern escreveu:
    >>>> PEBS cannot be used with guest mode. If user adds :p modifier set
    >>>> exclude_guest as well.
    >>>
    >>> Is this something Intel specific? Or can someone think of an arch where
    >>> this limitation wouldn't exist?
    >>
    >> Good point. So far precise_ip is used by arch/x86 only. I don't have an
    >> AMD based server so I don't know if there is a conflict between
    >> virtualization and IBS. Added Robert for advice.
    >
    > thanks for this hint.
    >
    > On AMD cpus precise_ip maps to IBS, which does not support hardware
    > options as perfctrs do. Thus, following attr flags are not supported:
    >
    > exclude_user, exclude_kernel, exclude_host, exclude_guest
    >
    > Counting in guest mode is possible with IBS, but not the exclusion of
    > a certain mode. If precise_ip counting is enabled on AMD we may not
    > set the exclude_guest flag.

    Ok, so with AMD precise_ip requires exclude_guest to be unset; for Intel
    we need it set.

    So then we look at vendor_id in /proc/cpuinfo?

    David


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