Messages in this thread | | | Date | Mon, 16 Sep 2013 22:14:08 -0600 | From | David Ahern <> | Subject | Re: [PATCH] perf session: Add option to copy events when queueing |
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On 9/16/13 10:40 AM, Frederic Weisbecker wrote: >> Yes. I could make it the default behavior; just overhead in doing >> that (malloc/copy for each event). > > Are there any tool that don't suffer from this bug somehow? If not then it must > be applied unconditionally.
I believe only 'live' commands would be affected: top, kvm stat live, my local scheduling daemon. perf-trace bypasses session and time ordering (though I question that decision).
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>> size of event is determined by mmap_event (mmap2_event in latest >> code) which is > 4096 because of the filename argument. Including >> the event directly in sample_queue would balloon memory usage >> (learned this the hard way!). > > Ah then perhaps we can allocate with the dynamic size of the event?
Yes, that's how I have it my patch -- allocate memory based on header size and copy in the queue_event function. I think we agree on this part now.
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>>> Although the mirrored os->sample_buffer condition check is a bit ugly and should move to >>> a function. But the idea is there. >> >> Ok. That should be a separate patch. Are you going to submit that one? > > Yeah, unless you beat me at it :)
That's not going to happen on my end due to a recent time constraint (jury duty - minimum 1 week trial). At best I can do a patch in early October.
David
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