Messages in this thread | | | Date | Thu, 09 Feb 2012 07:43:20 -0700 | From | David Ahern <> | Subject | Re: perf: record segfaults for cycles event when collecting data on a VM |
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On 02/09/2012 06:34 AM, Ingo Molnar wrote: > > * Joerg Roedel <joerg.roedel@amd.com> wrote: > >> On Thu, Feb 09, 2012 at 08:30:24AM +0100, Ingo Molnar wrote: >>> >>> * Joerg Roedel <joerg.roedel@amd.com> wrote: >>> >>>>> which makes sense. It forces >>>>> perf_session__find_machine_for_cpumode() to return the host >>>>> machine always. >>>> >>>> Great, thanks. I will send two patches tomorrow to fix Jason's >>>> problem and change the default for perf_guest. >>> >>> Well, if the crash is fixed then the the default can stay, >>> right? >> >> David's crash is fixed by changing the default back to its >> original value :) > > Then that's the wrong fix really.
You can't enable perf_guest unless guest info has been configured as done with perf-kvm.
The problem is triggered in perf_session__find_machine_for_cpumode(). If perf_session__find_machine() is changed to perf_session__findnew_machine() you get into machines__findnew() which shows the root cause: the event is for a VM but symbol_conf.guestmount is not set.
So, really perf_guest cannot be enabled unless guest info has been given.
David
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