On 02/15/2011 11:25 AM, William Cohen wrote:
> On 02/15/2011 10:53 AM, Julien Desfossez wrote:
>> LTTng-UST vs SystemTap userspace tracing benchmarks
>>
>> February 15th, 2011
>>
>> Authors: Mathieu Desnoyers <[email protected]>
>> Julien Desfossez <[email protected]>
>
>> * SystemTap probe (stap testutrace.stp -F) :
>> probe process("./.libs/tracepoint_benchmark").mark("single_trace") {
>> printf("%d : %s\n", gettimeofday_ns(), $arg1);
>> }
Hi William,
> How much of the SystemTap overhead is due to the printf() statement in the
> probe? What is the run time for the following:
>
> probe process("./.libs/tracepoint_benchmark").mark("single_trace") {}
Except the fact that it produces a warning because the probe is empty,
the results differ a little but not as much as I expected. I also tested
(in flight recorder mode) with just removing the gettimeofday_ns() call
(and printing) :
# of threads With printf Without gtod_ns() Without printf
1 0:58.36 0:52.27 0:46.45
2 1:49.94 1:37.61 1:27.33
4 2:38.49 2:35.13 2:50.87
> Is the code for the benchmarks available, so we can take a look at reducing
> the overhead of SystemTap?
For those who want to play with the benchmark, we setup a git repository
here : git://git.lttng.org/benchmarks.git
If you have any suggestions or ideas to make these tests better, we'll
be happy to integrate it.
Thanks,
Julien
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