Date: Mon, 8 Jul 2013 13:54:01 -0700
From: Andi Kleen <ak@linux.jf.intel.com>
To: Dave Hansen <dave@sr71.net>
Cc: Stephane Eranian <eranian@google.com>, Dave Hansen <dave.hansen@intel.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <peterz@infradead.org>, "mingo@elte.hu" <mingo@elte.hu>,
        dave.hansen@linux.jf.intel.com, Jiri Olsa <jolsa@redhat.com>
Subject: Re: [PATCH] perf: fix interrupt handler timing harness
Message-ID: <20130708205401.GG5643@tassilo.jf.intel.com>
References: <20130704223010.GA30625@quad>
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 <CABPqkBRdK5WwokEWE3tQZiAyO3pWbS9aUn7HUkQT+XsMYfJUiA@mail.gmail.com>
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> I did a quite a bit of ftracing to look for spots inside the handler
> which were taking large amounts of time.  There were none.  The
> execution time was spread very evenly over the entire nmi handler.  It
> didn't appear to be any individual hot cachelines or doing something
> silly like sitting in a loop handling lots of PMU events.

In some cases callgraphs seemed to be quite expensive (large fraction
of the handler time)

-Andi
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