Messages in this thread | | | Date | Mon, 6 Sep 2010 14:40:46 +0200 | From | Ingo Molnar <> | Subject | Re: disabling group leader perf_event |
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* Peter Zijlstra <peterz@infradead.org> wrote:
> On Mon, 2010-09-06 at 14:58 +0300, Avi Kivity wrote: > > On 09/06/2010 02:54 PM, Peter Zijlstra wrote: > > > > > >> Basically, to read() all events in one go. I have many of them. > > >> > > >> My current problem is that I have an event (kvm_exit) which I want to > > >> drill down by looking at a field (exit_reason). So I create lots of > > >> separate perf_events with a filter for each reason: > > >> kvm_exit(exit_reason==0), kvm_exit(exit_reason==1), etc. But filters > > >> are fairly slow (can have ~60 such events on AMD), so I want to make > > >> this drill-down optional. > > > Yeah, filters suck. > > > > Any idea why? I saw nothing obvious in the code, except that there > > is lots of it. > > It filters after it does all the hard work of creating the trace > event, instead of before.
Btw., that's an implementational property of filters that would be nice to fix.
If it's not doable within CPP then outside of it.
Ingo
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