[lttng-dev] Question about the performance of LTTng-UST

[changz]

Hi All,

I wrote a very simple test code like this:

         for (i = 0; i < 0xffffff; i++) {
                 tracepoint(sample_component, message, "This is a 
performance test:","main",i);
         }

And then I started lttng and ran the test code:
time  ./test
real0m16.120s
user0m8.280s
sys0m7.789s

 From the result of time output, you can see sys time is about half of 
the whole run-time. I wondered where the cost was from.
So I used strace to track it and found amount of system calls (get_cpu 
and clock_gettime) during the run-time.
I know these system calls are used for ring-buffer. But I just think the 
cost is a little heavy.

What do you think?

BR
Zheng
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