Re: [PATCH] perf: remove PERF_SAMPLE_RAW

From: Peter Zijlstra
Date: Thu Aug 27 2009 - 05:06:02 EST

On Thu, 2009-08-27 at 10:43 +0200, Ingo Molnar wrote:
> * Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> > Apparently people think trace-events became an ABI the moment perf
> > exported them, regardless what the text surrounding
> > PERF_SAMPLE_RAW said about the opaqueness of the data provided.
> Well it's still opaque and the descriptor of what it means is in
> debugfs so it's not an ABI as the comment says.

Clearly people their expectations didn't match this.

> > I'm not willing to make anything trace related into an ABI, hence
> > remove this.
> This removes quite a bit of nice functionality we already have, so i
> think it's (way) too heavy handed.
> I think what we want is the golden middle: a per tracepoint
> property. I.e. we would provide:
> or TRACE_EVENT_CORE() or TRACE_EVENT_ABI() - which carries a 'will
> maintain this as an ABI' promise from the maintainer who adds it.
> Also, tracepoints are a unidirectional channel of information - in
> practice those are way easier to handle as an ABI than other ABIs
> such as behavior, semantics, etc. So i'd expect there to be a
> healthy set of 'stable' tracepoints.

Whatever works for people really, I just want this discussed. I'm not at
all ready to have everything TRACE_EVENT() declared an ABI as it stands
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