From f1c6a58121f9846ac665b0fbd3cbab90ce8bcbac Mon Sep 17 00:00:00 2001 From: Daniel Qarras Date: Sun, 12 Jul 2009 04:32:40 -0700 Subject: [PATCH] perf_counter, x86: Extend perf_counter Pentium M support I've attached a patch to remove the Pentium M special casing of EMON and as noticed at least with my Pentium M the hardware PMU now works: Performance counter stats for '/bin/ls /var/tmp': 1.809988 task-clock-msecs # 0.125 CPUs 1 context-switches # 0.001 M/sec 0 CPU-migrations # 0.000 M/sec 224 page-faults # 0.124 M/sec 1425648 cycles # 787.656 M/sec 912755 instructions # 0.640 IPC Vince suggested that this code was trying to address erratum Y17 in Pentium-M's: http://download.intel.com/support/processors/mobile/pm/sb/25266532.pdf But that erratum (related to IA32_MISC_ENABLES.7) does not affect perfcounters as we dont use this toggle to disable RDPMC and WRMSR/RDMSR access to performance counters. We keep cr4's bit 8 (X86_CR4_PCE) clear so unprivileged RDPMC access is not allowed anyway. Cc: Vince Weaver Cc: Peter Zijlstra Cc: Stephane Eranian LKML-Reference: Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_counter.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c index bed1c4c2f25..7e346d4bc0f 100644 --- a/arch/x86/kernel/cpu/perf_counter.c +++ b/arch/x86/kernel/cpu/perf_counter.c @@ -1583,10 +1583,8 @@ static int p6_pmu_init(void) break; case 9: case 13: - /* for Pentium M, we need to check if PMU exist */ - rdmsr(MSR_IA32_MISC_ENABLE, low, high); - if (low & MSR_IA32_MISC_ENABLE_EMON) - break; + /* Pentium M */ + break; default: pr_cont("unsupported p6 CPU model %d ", boot_cpu_data.x86_model); -- 2.32.0.93.g670b81a890