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SubjectRe: perf: regression -- missing /sys/devices/system/cpu/perf_events

* Vince Weaver <vweaver1@eecs.utk.edu> wrote:

> On Tue, 24 May 2011, Ingo Molnar wrote:
> >
> > So, what is wrong with the method Peter suggested: the presence of the perf
> > syscall (it not returning -ENOSYS) is bona fide evidence that perf is
> > available.
>
> it's just hard to do that from a shell script.

Yeah.

> also, running the perf syscall can be tricky if you have a new kernel but an
> older set of header files that doesn't have the syscall number defined.

I suspect you could add some quick band-aid like:

#ifndef __NR_perf_event_open
# ifdef __i386__
# define __NR_perf_event_open 336
# endif
# ifdef __x86_64__
# define __NR_perf_event_open 298
# endif
# ifdef __powerpc__
# define __NR_perf_event_open 319
# endif
# ifdef __arm__
# define __NR_perf_event_open 364
# endif
#endif

#ifndef __NR_perf_event_open
# error Please add the __NR_perf_event_open definition for this architecture!
#endif

This should cover 99% of the users - and fill in the table as people report
build failures :)

Thanks,

Ingo


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