[ltt-dev] Kernel and User Space tracers have different timestamp reference

[Mathieu Desnoyers]

Hi!

Yesterday evening, Julien and I were actively finishing the vDSO work
that is needed to have synchronized timestamps between the kernel LTTng
and UST on x86. It should be ready very soon. Keep posted for a new
release. :)

By the way, in the initial implementation, only 64-bit processes on
64-bit x86 systems with synchronized TSCs will benefit from the vDSO
speed. All other x86 setups will fallback on a system call, which will
still work, albeit being a bit slower.

Thanks,

Mathieu

* Alexandre Montplaisir (alexandre.montplaisir at polymtl.ca) wrote:
> Hi folks,
>
> I've received this bug report about kernel/UST trace synchronization.  
> Anyone knows what's the status on this?
>
> Thanks,
> Alexandre
>
>
> On 10-11-26 03:24 AM, Florent Boudet wrote:
>> Hello,
>>
>> I am sorry to contact you directly instead of filling a bug, but it
>> seems the option is disabled on the launchpad project...
>>
>> I have recorded userspace traces at the same time as kernel traces, and
>> opened both with LTTv.
>> Timestamp for userspace traces and timestamp for kernel traces have
>> different origins, which make it difficult to analyze.
>> I am not sure about the cause, this might be related to a GMT/localtime
>> issue...
>>
>> Regards,
>> Florent Boudet
>
>
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-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com