[lttng-dev] tracing page_faults with lttng?

[Francis Deslauriers]

Le sam. 2 nov. 2019, à 11 h 41, Milian Wolff via lttng-dev
<lttng-dev at lists.lttng.org> a écrit :
>
> On Samstag, 12. Oktober 2019 23:31:51 CET Milian Wolff via lttng-dev wrote:
> > On Montag, 29. Mai 2017 10:44:50 CEST Milian Wolff wrote:
> > > On Wednesday, May 24, 2017 6:26:38 PM CEST Francis Deslauriers wrote:
> > > > Hi Milian,
> > > > Are you running on an x86 processor?
> > >
> > > Yes, Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz.
> > >
> > > > The pagefault tracepoints are called : x86_exceptions_page_fault_user,
> > > > x86_exceptions_page_fault_kernel
> > > > Can you see those tracepoints when you run: lttng list --kernel
> > >
> > > Yes:
> > >
> > > $ lttng list --kernel | grep fault
> > >
> > >       x86_exceptions_page_fault_user (loglevel: TRACE_EMERG (0)) (type:
> > > tracepoint)
> > >
> > >       x86_exceptions_page_fault_kernel (loglevel: TRACE_EMERG (0)) (type:
> > > tracepoint)
> > >
> > >       kvm_async_pf_doublefault (loglevel: TRACE_EMERG (0)) (type:
> > > tracepoint)
> >
> > Hey there,
> >
> > a follow up to the above question: What about tracing page faults on ARM?
> > Perf can do that, but I see no page_fault trace points in the output of
> > `lttng list -k`?
>
> ping?

Hi Milian,

I believe that the page fault event you see with Perf is a perf event,
not a trace event. What is the name of the event you see exactly?
In order to trace the page faults on Arm with LTTng, we will need to
add trace event tracepoints to the do_page_fault() functions in the
arm (or arm64) architecture of the kernel.



Francis



>
> --
> Milian Wolff | milian.wolff at kdab.com | Senior Software Engineer
> KDAB (Deutschland) GmbH, a KDAB Group company
> Tel: +49-30-521325470
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-- 
Francis Deslauriers
Computer Engineer
EfficiOS inc.