From mboxrd@z Thu Jan 1 00:00:00 1970 From: julien.desfossez@polymtl.ca (Julien Desfossez) Date: Thu, 17 Feb 2011 11:20:51 -0500 Subject: [ltt-dev] LTTng-UST vs SystemTap userspace tracing benchmarks In-Reply-To: <4D5AA8F4.8060902@redhat.com> References: <4D5AA164.1050607@polymtl.ca> <4D5AA8F4.8060902@redhat.com> Message-ID: <4D5D4AE3.4070703@polymtl.ca> 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 >> Julien Desfossez > >> * 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