From bd2b5b12849a3446abad0b25e920f86f5480b309 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Wed, 10 Jun 2009 13:40:57 +0200
Subject: perf_counter: More aggressive frequency adjustment

Also employ the overflow handler to adjust the frequency, this results
in a stable frequency in about 40~50 samples, instead of that many ticks.

This also means we can start sampling at a sample period of 1 without
running head-first into the throttle.

It relies on sched_clock() to accurately measure the time difference
between the overflow NMIs.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 include/linux/perf_counter.h | 1 +
 1 file changed, 1 insertion(+)

(limited to 'include')

diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 3586df8..282d8cc 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -371,6 +371,7 @@ struct hw_perf_counter {
 
 	u64				freq_count;
 	u64				freq_interrupts;
+	u64				freq_stamp;
 #endif
 };
 
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