Messages in this thread | | | Date | Tue, 05 Jun 2012 11:12:03 -0600 | From | David Ahern <> | Subject | Re: git bisect and perf |
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On 6/5/12 10:05 AM, Peter Zijlstra wrote: > On Tue, 2012-06-05 at 18:00 +0200, Peter Zijlstra wrote: >> On Tue, 2012-06-05 at 09:29 -0600, David Ahern wrote: >>> I am trying find out when (ie. which commit) the pebs feature >>> actually >>> started working on a westmere system >> >> What do you mean with working? The whole cycles:pp thing is magic and >> unrelated to 'regular' PEBS stuff.
:p requires PEBS?
> .35 would indeed be the version we >> introduced PEBS support and it should actually work.
I'm referring to cycles:p
model name : Intel(R) Xeon(R) CPU E5620 @ 2.40GHz Fedora 14, 2.6.35.14-106.fc14.x86_64 (few perf_event* differences from 2.6.35.14).
# perf record -e cycles:p -v -- sleep 1
Warning: ... trying to fall back to cpu-clock-ticks
...
Cycles is supported; it's the :p that is not. perf userspace only recently gained the knowledge for discriminating the two. Using perf from acme/perf/urgent:
# /tmp/pbuild/perf record -e cycles:p -v -- sleep 1
Error: sys_perf_event_open() syscall returned with 28 (No space left on device). /bin/dmesg may provide additional information.
I chased this to intel_pebs_constraints() returning &emptyconstraint which has a weight of 0 (validate_event -> intel_get_event_constraints -> intel_pebs_constraints).
>> >> But if you're looking for the cycles:pp stuff (commit 7639dae0ca1) >> that's .38-rc1-ish. > > So on kernels pre that commit you could still do: > > perf record -e r108000c0:pp
Indeed that works on the F14 kernel.
David
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