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On 08/17/2016 09:35 PM, Frank Ch. Eigler wrote:
Hi - On Wed, Aug 17, 2016 at 09:30:38PM +0300, Avi Kivity wrote:[...]My load indeed calls epoll_wait() at a high rate, with zero timeout.[...]Yes. It's not very common, but some high throughput or latency sensitive applications will poll. In my case it's both high throughput and latency sensitive.Interesting. I assume you've measured that.[...]looks for mmap/exec syscalls. Perhaps there could be a mode (a -D setting?) for selecting kprobes rather than syscall-tracepoints to catch those events.Why not trace just mmap and exec syscalls, rather than everything? Surely there's a static tracepoint for those.Heh, in this case it's "surely not". :-) There exists only a multiplexed system-call-entry and a system-call-exit pair of tracepoints.
Hi,Should I wait for ongoing improvement here, or shall I look elsewhere for my tracing needs?
It would be a pity (for me) if I have to find another solution, because systemtap has all the expressiveness and integration I need. But it has a dramatic impact on my application runtime.
I was able to extract some useful data with perf probe/perf record, but as soon as I need to qualify a probe point with runtime information, perf falls short.
Avi
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