Accessing CPU performance counters from user space

Hi All,

Is it possible to access cpu performance counters from user space?
AFAIK, it is not possible.
I am aware of various attempts like perfmon and perfctr patch set.
Looks like a kernel module is
mandatory to access these registers. My objective is to measure
various parameters like number
instructions retired, number of cache misses, number of brach mis
predictions etc.

I know of an alternative way to count the number of instructions by
using ptrace but I think this approach
is very slow.

Regards,
Sandeep.
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Re: Accessing CPU performance counters from user space

On Thu, Jun 25, 2009 at 6:58 PM, sandeep lahane m> wrote:
> Hi All,
>
> Is it possible to access cpu performance counters from user space?
> AFAIK, it is not possible.

yes, impossible...because u need ring 0 to access these counter.

=46or some more info:

http://www.scl.ameslab.gov/Projects/Rabbit/menu.html#downloa d

and this one (irrelevant to linux kernel, but it shows how other
kernel are doing it.....all have to be ring0):

http://www.opensolaris.org/os/project/intel-platform/CPC/

> I am aware of various attempts like perfmon and perfctr patch set.
> Looks like a kernel module is
> mandatory to access these registers. My objective is to measure
> various parameters like number
> instructions retired, number of cache misses, number of brach mis
> predictions etc.
>
> I know of an alternative way to count the number of instructions by
> using ptrace but I think this approach
> is very slow.
>
> Regards,
> Sandeep.
> --
> To unsubscribe from this list: send the line "unsubscribe linux-newbi=
e" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at =A0http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.linux-learn.org/faqs
>



--=20
Regards,
Peter Teoh
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