linux-kernel - [PATCH] perf, x86: Allow setting period 1

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Date:	Fri,  8 Mar 2013 15:24:30 -0800
From:	Andi Kleen <andi@...stfloor.org>
To:	a.p.zijlstra@...llo.nl
Cc:	mingo@...nel.org, linux-kernel@...r.kernel.org,
	Andi Kleen <ak@...ux.intel.com>
Subject: [PATCH] perf, x86: Allow setting period 1

From: Andi Kleen <ak@...ux.intel.com>

I had some requests for setting period 1, so that every event of something
is caught.  To my knowledge there is no limit to 1 on Intel hardware.
Just remove the check for minimum 2

If specific CPUs have problems we can black list them.

Signed-off-by: Andi Kleen <ak@...ux.intel.com>
---
 arch/x86/kernel/cpu/perf_event.c |    5 -----
 1 files changed, 0 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index bf0f01a..2b394ae 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -946,11 +946,6 @@ int x86_perf_event_set_period(struct perf_event *event)
 		hwc->last_period = period;
 		ret = 1;
 	}
-	/*
-	 * Quirk: certain CPUs dont like it if just 1 hw_event is left:
-	 */
-	if (unlikely(left < 2))
-		left = 2;
 
 	if (left > x86_pmu.max_period)
 		left = x86_pmu.max_period;
-- 
1.7.7.6

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