> That's what I thought, but benchmarking showed that there's > practically no difference. > The filter is a simple ID comparison of the form 'id % 1,000 == 0', > so 999 out of 1K tracepoints are filtered out. > Could you please point me to some references on this topic? What is the running time and trace size with tracing disabled, with tracing enabled unconditionally, and with tracing under condition? If tracing takes negligible time, filtering will not change much. Note that I have not experimented with the current UST filter implementation but with a similar facility in GDB and an in-kernel prototype.
This article is not directly related but discusses many of these issues http://benthamscience.com/open/tocsj/articles/V006/11TOCSJ.htm
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