Messages in this thread | | | Date | Tue, 16 Sep 2014 19:58:34 +0200 | From | Ingo Molnar <> | Subject | Re: [RFC 2/2] perf: Marker software event and ioctl |
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* Pawel Moll <pawel.moll@arm.com> wrote:
> On Tue, 2014-09-16 at 08:44 +0100, Ingo Molnar wrote: > > I think adding an ioctl to inject user-provided data into the > > event stream is sensible, as long as there's a separate 'user > > generated data' event for it, etc. > > > > The main usecase I could see would be to introduce a > > perf_printf() variant, supported by 'perf trace' by default, to > > add various tracable printouts to apps. > > > > Timestamps generated by apps would be another usecase. It would > > probably be wise to add a 32-bit (or 64-bit) message type ID, > > plus a length field, with a message type registry somewhere in > > tools/perf/ (and reference implementation for each new subtype), > > to keep things organized yet flexible going forward. > > Right, so this is pretty much what I got talking to Arnaldo... > > > { u64 type; /* 0 means zero-terminated string in data */ > > u32 size; > > char data[size]; } && PERF_SAMPLE_MARKER > > ... with one type - 0 - defined as a "universal" string (so any > possible tool knows what to do about it), the rest being left > to userspace (this "registry" you mention). > > Before I proceed any further, is the term "marker" acceptable? > Maybe a "printf" instead? Or a "log"? As we know naming is > often single most discussed subject when it comes to new things > in the kernel ;-)
Well, it's a user-space generated trace/event entry, so lets call it that?
Thanks,
Ingo
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