Re: [PATCH v5 00/17] perf c2c: Support data source and display for Arm64

Leo Yan
2022-08-12T15:20:30Z

On Fri, Aug 12, 2022 at 09:43:07AM -0300, Arnaldo Carvalho de Melo wrote:

[...]

> > One question: should I later continue to upstream the first patch for
> > syncing the kernel header perf_event.h after Peter.Z comes back?
>
> yes, and we may have to backtrack and find some other way to implement
> this if he is opposed, as he in the past didn't like
> perf_event_attr.type namespace being used by userspace only records such
> as PERF_RECORD_FINISHED_ROUND, PERF_RECORD_COMPRESSED, etc.
>
> In this case its different, I think its ok as we already have
> PERF_MEM_SNOOPX_FWD and PERF_MEM_SNOOPX_PEER probably will be emitted by
> the some of the architectures, from the kernel, right?

Yes, as I know x86 generates memory samples from kernel, and SNOOPX_PEER
can be a useful snooping flag for other archs.

As a last resort if SNOOPX_PEER is rejected, we can rollback to use
existed flag (like reusing PERF_MEM_SNOOPX_FWD), though this would be
ambiguous for expressing the memory operations on Arm64.

Thanks,
Leo