From: Ingo Molnar <mingo@elte.hu>
Date: Sun, 17 May 2009 08:04:45 +0000 (+0200)
Subject: perf_counter, x86: fix zero irq_period counters
X-Git-Tag: v2.6.31-rc1~383^2~259
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d2517a49d55536b38c7a87e5289550cfedaa4dcc;p=pandora-kernel.git

perf_counter, x86: fix zero irq_period counters

The quirk to irq_period unearthed an unrobustness we had in the
hw_counter initialization sequence: we left irq_period at 0, which
was then quirked up to 2 ... which then generated a _lot_ of
interrupts during 'perf stat' runs, slowed them down and skewed
the counter results in general.

Initialize irq_period to the maximum instead.

[ Impact: fix perf stat results ]

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---

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