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Date: Wed, 18 Mar 2015 12:18:25 -0700
From: Andi Kleen <ak@linux.intel.com>
To: Namhyung Kim <namhyung@kernel.org>
Cc: "Liang, Kan" <kan.liang@intel.com>, "acme@kernel.org" <acme@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "eranian@google.com" <eranian@google.com>, jolsa@kernel.org
Subject: Re: [PATCH 1/1] perf, tool: partial callgrap and time support in
 perf record
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> > The answer is no: it solves a different problem. Group read 
> > is just fine granuality counting. It cannot be used
> > to sample for multiple events in parallel.
> 
> But group read disables sampling for non-leader events so the number
> of total samples should be small, no?

Yes it's smaller, but it doesn't sample everything.

-Andi