Messages in this thread | | | Date | Tue, 5 May 2015 19:00:47 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH V7 3/6] perf, x86: handle multiple records in PEBS buffer |
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On Tue, May 05, 2015 at 04:36:51PM +0000, Liang, Kan wrote: > > > RECORDs are generic, and should live in the core code. > > > > > > Also, you should introduce this RECORD in a separate patch. > > > > On that, this is lacking a RECORD definition in > > include/uapi/linux/perf_event.h:perf_event_type > > The PERF_RECORD_LOST already defined in perf_event_type. > Are you suggesting to add a new dedicated RECORD type, like PERF_RECORD_COLLISION?
Yes, this should be a new RECORD, LOST_SAMPLES maybe.
The thing is, LOST is about the ring-buffer running out of space, this is very much not the case here. Reusing it like this creates the situation where userspace cannot tell what happened, and that is a very bad thing indeed.
What we want to convey is that we dropped/lost a (number of) sample(s).
So the objection against the RECORD_COLLISIONS name is that it names the reason we did something, but not the something we did.
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