Messages in this thread | | | Subject | Re: [PATCH v2 4/5] perf record: add meta-data support for pipe-mode | From | Peter Zijlstra <> | Date | Tue, 22 May 2012 19:33:55 +0200 |
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On Fri, 2012-05-18 at 14:19 -0300, Arnaldo Carvalho de Melo wrote:
> PeterZ was the one objecting to adding more userspace only events,
Ah, yes I was ;-)
So uhm the argument was something like perf_event_type is a kernel enum and userspace stealing space there is going to get us into trouble eventually since userspace doesn't register its types in our enum.
Furthermore most (if not all) the userspace thingies were setup (like in this case single session meta-data) things. So they don't belong in the event stream at all.
From what I can remember all this is somehow related to how data is passed to scripts or so and since there's only a single stdin everything is stuffed over it.
For the data file we should simply create another section in the header; and I think that is how it works these days.
For the script muck, I've really no idea how all that works, but why can't you wrap the stuff in another layer; have a header up front that says the next N bytes are meta-data and after that there's the regular data stream.
Or take some inspiration from one of the many multi-stream stream formats out there like mpeg or ogg or whatever.
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