linux-kernel - Re: [PATCH 05/34] perf, x86: Report PEBS event in a raw format

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Date:	Tue, 23 Oct 2012 14:31:14 +0200
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org, acme@...hat.com,
	eranian@...gle.com, Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 05/34] perf, x86: Report PEBS event in a raw format

On Thu, 2012-10-18 at 16:19 -0700, Andi Kleen wrote:
> +       if (event->attr.sample_type & PERF_SAMPLE_RAW) {
> +               raw.size = x86_pmu.pebs_record_size;
> +               raw.data = __pebs;
> +               data.raw = &raw;
> +       } 

The Changelog babbles about registers, yet you export the entire record.

There's the PERF_SAMPLE_REGS thing which has been pointed out to you,
but you fail to include this in your arguments.

Also, there's an alignment issue there, the raw.data is 32bit offset,
the record is u64 aligned, leaving the output stream offset, wrecking
things.

And as with any ABI extension, it should come with useful userspace to
make use of it.

I'll hold off on this one for now.
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