Messages in this thread | | | Date | Fri, 23 Oct 2015 14:52:11 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling |
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On Thu, Oct 22, 2015 at 06:28:22PM +0800, Wangnan (F) wrote: > information to analysis when glitch happen. Another way we are trying to > implement > now is to dynamically turn events on and off, or at least enable/disable > sampling dynamically because the overhead of copying those samples > is a big part of perf's total overhead. After that we can trace as many > event as possible, but only fetch data from them when we detect a glitch.
So why don't you 'fix' the flight recorder mode and just leave the data in memory and not bother copying it out until a glitch happens?
Something like this:
lkml.kernel.org/r/20130708121557.GA17211@twins.programming.kicks-ass.net
it appears we never quite finished that.
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