* [lttng-dev] Cross-domain influence on overhead
@ 2013-01-04 11:53 Oestman, Fredrik
2013-01-07 13:44 ` Mathieu Desnoyers
0 siblings, 1 reply; 3+ messages in thread
From: Oestman, Fredrik @ 2013-01-04 11:53 UTC (permalink / raw)
Hi,
I've noticed the following somewhat puzzling effect on both Intel and ARM architecture computers:
If all trace events are enabled in one domain only, either kernel or user space, and there are lots of static tracepoints instrumented in the other, then these inactive tracepoints start causing overhead of about the same magnitude as if they were active, as if trace events were enabled in this domain.
Is there any obvious explanation to this behaviour?
Cheers,
Fredrik ?stman
http://go.mentor.com/sourceryanalyzer/
^ permalink raw reply [flat|nested] 3+ messages in thread
* [lttng-dev] Cross-domain influence on overhead
2013-01-04 11:53 [lttng-dev] Cross-domain influence on overhead Oestman, Fredrik
@ 2013-01-07 13:44 ` Mathieu Desnoyers
2013-01-07 13:53 ` Oestman, Fredrik
0 siblings, 1 reply; 3+ messages in thread
From: Mathieu Desnoyers @ 2013-01-07 13:44 UTC (permalink / raw)
* Oestman, Fredrik (Fredrik_Oestman at mentor.com) wrote:
> Hi,
>
> I've noticed the following somewhat puzzling effect on both Intel and
> ARM architecture computers:
>
> If all trace events are enabled in one domain only, either kernel or
> user space, and there are lots of static tracepoints instrumented in
> the other, then these inactive tracepoints start causing overhead of
> about the same magnitude as if they were active, as if trace events
> were enabled in this domain.
>
> Is there any obvious explanation to this behaviour?
No, this would be really surprising.
Can you provide your test script, and more details about the way you
perform your benchmarks ? How is the overhead calculated ? From how many
tracepoints hit ? How many processes spawned/exec() done ? How many
tracepoints hit per process ?
Thanks,
Mathieu
>
> Cheers,
>
> Fredrik ?stman
>
> http://go.mentor.com/sourceryanalyzer/
>
>
> _______________________________________________
> lttng-dev mailing list
> lttng-dev at lists.lttng.org
> http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
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2013-01-04 11:53 [lttng-dev] Cross-domain influence on overhead Oestman, Fredrik
2013-01-07 13:44 ` Mathieu Desnoyers
2013-01-07 13:53 ` Oestman, Fredrik
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