profiling with node-profiler & d8: high number of unaccounted ticks

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Vivus Ignis

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Jun 20, 2011, 9:37:56 AM6/20/11
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Hello noders,

I'm trying to profile my little node app which is effectively a redis proxy. I've required bnoordhuis' profiler module and fed the resulting v8.log to linux-tick-processor. The output seems to me a bit weird:

<SNIP>
Statistical profiling result from /usr/local/repa/v8.log, (31043 ticks, 30884 unaccounted, 0 excluded).

[Unknown]:
ticks total nonlib name
30884 99.5%
(...)
</SNIP>

What does such a high number of unaccounted ticks mean?

p.s.: my host platform is opensolaris, node v0.4.8

Thanks in advance.

Vyacheslav Egorov

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Jun 20, 2011, 11:39:03 AM6/20/11
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Is C++ section of the output empty?

If yes then linux-tick-processor for some reason can't resolve ticks
that happen in native code. Maybe something is different with output
format for nm.

--
Vyacheslav Egorov

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dhruvbird

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Jun 21, 2011, 3:39:52 AM6/21/11
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Hello,

Maybe related, but I've had a pretty bad experience with the v8
profiler since it is sampling based. Every once in a while, the real
performance problem gets hidden. Not yet as reliable as gprof.

Regards,
-Dhruv.
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