From: David Ahern <dsahern@gmail.com>
To: Vince Weaver <vweaver1@eecs.utk.edu>
Cc: Ingo Molnar <mingo@elte.hu>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
linux-kernel@vger.kernel.org, paulus@samba.org, acme@redhat.com
Subject: Re: perf: regression -- missing /sys/devices/system/cpu/perf_events
Date: Tue, 24 May 2011 14:57:22 -0600 [thread overview]
Message-ID: <4DDC1BB2.4090503@gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.00.1105241610390.24062@cl320.eecs.utk.edu>
On 05/24/11 14:12, Vince Weaver 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.
What about kallsyms:
grep sys_perf_event_open /proc/kallsyms
even with the new security feature you should be able to see that it
exists. The name has been the same since the counters->events rename in
cdd6c48. egrep for both names for kernels older than 2.6.31.
David
>
> 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.
>
> Vince
> vweaver1@eecs.utk.edu
> --
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next prev parent reply other threads:[~2011-05-24 20:57 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-24 13:59 perf: regression -- missing /sys/devices/system/cpu/perf_events Vince Weaver
2011-05-24 14:11 ` Peter Zijlstra
2011-05-24 17:42 ` Vince Weaver
2011-05-24 19:48 ` Ingo Molnar
2011-05-24 20:12 ` Vince Weaver
2011-05-24 20:57 ` David Ahern [this message]
2011-05-24 21:29 ` Ingo Molnar
2011-06-03 21:54 ` [patch] perf - comment /proc/sys/kernel/perf_event_paranoid to be part of user ABI Vince Weaver
2011-06-04 10:23 ` Ingo Molnar
2011-06-04 11:06 ` [tip:perf/core] perf: Comment " tip-bot for Vince Weaver
2011-05-24 21:37 ` perf: regression -- missing /sys/devices/system/cpu/perf_events Ingo Molnar
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