Re: [RFC PATCH] perf: Add load latency monitoring on Intel Nehalem/Westmere

Lin Ming
2010-12-23T08:24:52Z

On Wed, 2010-12-22 at 18:45 +0800, Peter Zijlstra wrote:
> On Wed, 2010-12-22 at 11:08 +0100, Stephane Eranian wrote:
> > Yes, I think there is more to it than just data source, unfortunately.
> > If you want to avoid returning an opaque u64 (PERF_SAMPLE_EXTRA), then
> > you need to break it down: PERF_SAMPLE_DATA_SRC, PERF_SAMPLE_XX
> > and so on.
>
> I guess we can do things like:
>
> Satisfied by {L1, L2, L3, RAM}x{snoop, local, remote} + unknown, and
> encode "Pending core cache HIT" as L2-snoop or something, whatever is
> most appropriate.
>
> But does that cover every architecture?
>
> Also, since that doesn't require more that 4 bits to encode, we could
> try and categorize what else is around and try and create a well
> specified _EXTRA register, I mean, we still got 60bits left after this.

Could you tell more about this well specified _EXTRA register?