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From:   Alexander Shishkin <alexander.shishkin@linux.intel.com>
To:     Arnaldo Carvalho de Melo <acme@redhat.com>
Cc:     Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org,
        kan.liang@linux.intel.com, Adrian Hunter <adrian.hunter@intel.com>,
        alexander.shishkin@linux.intel.com
Subject: Re: [PATCH v6 7/7] perf intel-pt: Add brief documentation for PEBS via Intel PT
In-Reply-To: <20190813141453.GB3754@redhat.com>
References: <20190806084606.4021-1-alexander.shishkin@linux.intel.com> <20190806084606.4021-8-alexander.shishkin@linux.intel.com> <20190813135149.GA3754@redhat.com> <87imr12m9x.fsf@ashishki-desk.ger.corp.intel.com> <20190813141453.GB3754@redhat.com>
Date:   Tue, 13 Aug 2019 19:21:39 +0300
Message-ID: <87ftm52fzg.fsf@ashishki-desk.ger.corp.intel.com>
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Arnaldo Carvalho de Melo <acme@redhat.com> writes:

> I've just blindly followed the provided documentation :)

Yes, I should have checked it also before I sent it out. :)

> So you say I should have tried this instead:
>
>   # perf record -c 10000 -e '{intel_pt/branch=0/,cycles/aux-output/ppp}' uname

Right. For the purposes of illustrating the error condition, you can
probably drop the '-c ...' and 'branch=0' also, but either way is fine.

>   Error:
>   The 'aux_output' feature is not supported, update the kernel.

Or it's not supported by the hardware. I don't think we make a
distinction at the moment. You can tell if it's available from dmesg,
but not otherwise.

>   #
>
> Or with leader sampling?
>
>   # perf record -c 10000 -e '{intel_pt/branch=0/,cycles/aux-output/ppp}:S' uname

Not sure if we should even allow this. Maybe Adrian can chime in.

Thanks,
--
Alex