Messages in this thread | | | Date | Wed, 8 Feb 2012 18:44:34 +0100 | From | Joerg Roedel <> | Subject | Re: perf: record segfaults for cycles event when collecting data on a VM |
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On Wed, Feb 08, 2012 at 09:55:35AM -0700, David Ahern wrote: > perf record -e cycles -p 21483 -- sleep 1 > [ perf record: Woken up 1 times to write data ] > [ perf record: Captured and wrote 0.012 MB perf.data (~503 samples) ] > Segmentation fault
The problem is similar to the one Jason is seeing. I am working on a fix right now. Bottom line is that the perf-tool may receive samples tagged as GUEST_KERNEL even when guest-sampling is disabled (probably a race-condition). The perf-tool can not find a valid machine pointer for such a sample and passes NULL down to the other functions. And some functions don't seem to handle this.
David, can you try to change the default for perf_guest back to false amd re-test? Not with 'sleep 1' probably, on my setup it takes a busy guest and a few seconds to trigger.
Joerg
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