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<p class="MsoNormal"><span style="font-size:11.0pt">We are trying to use user space LTTng to perform some performance analysis of fast-path layer 3 forwarding. We have seen that with the tracepoints enabled, we experience about a 30% increase in service time.
This is spread out over two tracepoints so each one is still contributing a good amount.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">This fast path is fast, about 300 cycles so we are asking a lot of efficiency of the tracepoint but for comparison, we implemented a simple ring buffer. When we run with this type of capture, we only experience
a 5% increase in service time.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">I’m looking for pointers. We’d rather use LTTng. Are there ways to tune LTTng ust for ultra high performance requirements. Perhaps there is a way we could write directly to ust’s ring buffers, or perhaps
preallocate the buffers?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Rich<o:p></o:p></span></p>
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