Re: [PATCH] perf: revert PERF_RECORD_MMAP2 support

From: Ingo Molnar
Date: Wed Oct 16 2013 - 05:30:24 EST



* Stephane Eranian <eranian@xxxxxxxxxx> wrote:

> > For example by a simple patch that returns -EINVAL (or -ENOSYS) if the
> > new flag is used - i.e. behaves like the old kernel in that regard -
> > but leaves the rest in place. (the 'rest' will hopefully be fixed for
> > v3.13)
>
> That's what I did in my initial revert patch. But it did not include the
> perf tool revert.

Could the perf tool part have a minimal revert as well?

> I believe in the end, we will still go with the extended MMAP record and
> not with the physical address (which adds a PERF_SAMPLE_*). So we can
> leave the attr->mmap2 bit defined and return -EINVAL for now.

Yeah.

> As for the perf tool, we can remove everything and add that later on
> because the layout of the MMAP2 record may change.

Yes - but can we keep the actual revert patch minimal? I.e. just prevent
mmap2 records from being generated, or so.

Thanks,

Ingo
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