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Subject: Re: [BUG] perf_event: sampling buffer format cannot handle
 multi-event sampling
From: Peter Zijlstra <peterz@infradead.org>
To: Stephane Eranian <eranian@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
        Arnaldo Carvalho de Melo <acme@redhat.com>, mingo@elte.hu,
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        Robert Richter <robert.richter@amd.com>,
        Andi Kleen <andi@firstfloor.org>
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Date: Tue, 19 Apr 2011 23:20:56 +0200
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On Tue, 2011-04-19 at 21:16 +0000, Stephane Eranian wrote:
> > Or simply don't mix different sample_types in the same buffer?
> >
> Does the kernel disallow this when you merge the output via that
> ioctl()? 

No, it will happily comply and provide you with hard to parse output.
Just don't do that if you're not willing to untangle it ;-)