On 09/03/2010 01:37 PM, David Goulet wrote:
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Hi everyone,
I think we had some time ago a discussion about that but now I want to fix this
properly and for good. The current benchmark test in the UST git is :
1) Only testing trace_mark
2) Using syscalls
This makes the per event time goes ~1.1ms for 1 millions events. I did some time
Are you sure about this? I get around 1 us/event.
ago another benchmark test that tested trace_mark, tracepoint with trace_mark
and custom probe but _without_ syscalls (only math calculation) and the time
dropped to ~200ns per event.
Can you explain why system calls make such a big difference in per-event
times? I find it disturbing and I am reluctant to remove them from the
benchmark just because this results in better figures without knowing
what is happening.
So, I don't question the current benchmark test but perhaps it should be good to
design a test that first will test all "marking" technology (including soon to
come trace_event), second that will use multiple use case scenario (like
syscalls, regular calculation, string manipulation, I/O, ...) because each of
these test gives different results.
We have NO test case that test all four (marker, TP, custom, TE) and I think
this should be VERY important because I just found out that the the
trace_mark_tp was not working since the changes made by Nils with the data
pointer by using some old test I had. This should be detected with the
tests/runtests script at each new release or/and pull commit.
Good ideas, but I think tests and benchmarks should be separate
programs. Probably there should be one test per instrumentation type and
one benchmark per instrumentation type.
pmf
Cheers
David
- --
David Goulet
LTTng project, DORSAL Lab.
1024D/16BD8563
BE3C 672B 9331 9796 291A 14C6 4AF7 C14B 16BD 8563
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