Re: [GIT PULL] perf fixes

[Stephane Eranian]

On Thu, Mar 14, 2013 at 11:53 PM, Stephane Eranian <eranian@xxxxxxxxxx> wrote:
> On Thu, Mar 14, 2013 at 11:42 PM, Stephane Eranian <eranian@xxxxxxxxxx> wrote:
>> On Thu, Mar 14, 2013 at 11:19 PM, Stephane Eranian <eranian@xxxxxxxxxx> wrote:
>>> On Thu, Mar 14, 2013 at 11:17 PM, Linus Torvalds
>>> <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>>>> On Thu, Mar 14, 2013 at 3:09 PM, Stephane Eranian <eranian@xxxxxxxxxx> wrote:
>>>>>
>>>>> Could be related to suspend/resume. But were you running perf across
>>>>> that resume/suspend cycle?
>>>>
>>>> No.
>>>>
>>>> In most cases I was running a perf record before and after (but not
>>>> *while* suspending)
>>>>
>>>> In at least one other crash, I didn't run perf before at all, so the
>>>> first time I used perf was after the resume.
>>>>
>>>> So in no cases did I actually have any perf stuff active over the
>>>> suspend itself.
>>>>
>>> Ok, simpler test case then.
>>>
>>>>> Let's see if we can reproduce the problem on the same ChromeBook you
>>>>> have. Don't have one myself.
>>>>
>>>> I don't imagine it should be about chromebook per se, because afaik
>>>> all of pmu suspend/resume is done by the kernel, no firmware involved.
>>>>
>>>> So I'd assume it should happen with any IvyBridge.
>>>>
>>> Will try on a desktop IvyBridge too.
>>
>> Ok, it happens on my IVB desktop too, so I can investigate...
>
> It's not specific to IVB either, it hangs on my Nehalem desktop as well.

Looks related to PEBS. If I drop the :pp the machine does not hang. Even
a single :p hangs it. So it is possible something is not properly
restored in the
DS state after a resume or is corrupted by the suspend.
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