linux-kernel - [PATCH -tip] perf_counter/x86: Add a quirk for Atom processors

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Message-ID: <20090612080855.GA2286@ywang-moblin2.bj.intel.com>
Date:	Fri, 12 Jun 2009 16:08:55 +0800
From:	Yong Wang <yong.y.wang@...ux.intel.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH -tip] perf_counter/x86: Add a quirk for Atom processors

The fixed-function performance counters do not work on current Atom
processors. Use the general-purpose ones instead.

Signed-off-by: Yong Wang <yong.y.wang@...el.com>

---
 perf_counter.c |    6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
index 895c82e..4bba0d8 100644
--- a/arch/x86/kernel/cpu/perf_counter.c
+++ b/arch/x86/kernel/cpu/perf_counter.c
@@ -968,6 +968,12 @@ fixed_mode_idx(struct perf_counter *counter, struct hw_perf_counter *hwc)
 	if (!x86_pmu.num_counters_fixed)
 		return -1;
 
+        /* 
+	 * Quirk: IA32_FIXED_CTRs do not work on current Atom processors  
+	 */
+	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL && boot_cpu_data.x86_model == 28)
+		return -1;
+
 	event = hwc->config & ARCH_PERFMON_EVENT_MASK;
 
 	if (unlikely(event == x86_pmu.event_map(PERF_COUNT_HW_INSTRUCTIONS)))
--
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