Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753669AbaGVIKP (ORCPT ); Tue, 22 Jul 2014 04:10:15 -0400 Received: from mga01.intel.com ([192.55.52.88]:46705 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753206AbaGVIKM (ORCPT ); Tue, 22 Jul 2014 04:10:12 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.01,708,1400050800"; d="scan'208";a="573497466" From: "Yan, Zheng" To: linux-kernel@vger.kernel.org Cc: a.p.zijlstra@chello.nl, mingo@kernel.org, acme@infradead.org, eranian@google.com, andi@firstfloor.org, "Yan, Zheng" Subject: [PATCH v3 3/9] perf, x86: use the PEBS auto reload mechanism when possible Date: Tue, 22 Jul 2014 16:09:56 +0800 Message-Id: <1406016602-31845-4-git-send-email-zheng.z.yan@intel.com> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1406016602-31845-1-git-send-email-zheng.z.yan@intel.com> References: <1406016602-31845-1-git-send-email-zheng.z.yan@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When a fixed period is specified, this patch make perf use the PEBS auto reload mechanism. This makes normal profiling faster, because it avoids one costly MSR write in the PMI handler. Signef-off-by: Yan, Zheng --- arch/x86/kernel/cpu/perf_event.c | 15 +++++++++------ arch/x86/kernel/cpu/perf_event.h | 1 + arch/x86/kernel/cpu/perf_event_intel_ds.c | 9 +++++++++ 3 files changed, 19 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 8868e9b..60593bc 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -979,13 +979,16 @@ int x86_perf_event_set_period(struct perf_event *event) per_cpu(pmc_prev_left[idx], smp_processor_id()) = left; - /* - * The hw event starts counting from this event offset, - * mark it to be able to extra future deltas: - */ - local64_set(&hwc->prev_count, (u64)-left); + if (!(hwc->flags & PERF_X86_EVENT_AUTO_RELOAD) || + local64_read(&hwc->prev_count) != (u64)-left) { + /* + * The hw event starts counting from this event offset, + * mark it to be able to extra future deltas: + */ + local64_set(&hwc->prev_count, (u64)-left); - wrmsrl(hwc->event_base, (u64)(-left) & x86_pmu.cntval_mask); + wrmsrl(hwc->event_base, (u64)(-left) & x86_pmu.cntval_mask); + } /* * Due to erratum on certan cpu we need diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h index d8165f3..fa8dfd4 100644 --- a/arch/x86/kernel/cpu/perf_event.h +++ b/arch/x86/kernel/cpu/perf_event.h @@ -69,6 +69,7 @@ struct event_constraint { #define PERF_X86_EVENT_PEBS_ST 0x2 /* st data address sampling */ #define PERF_X86_EVENT_PEBS_ST_HSW 0x4 /* haswell style st data sampling */ #define PERF_X86_EVENT_COMMITTED 0x8 /* event passed commit_txn */ +#define PERF_X86_EVENT_AUTO_RELOAD 0x10 /* use PEBS auto-reload */ struct amd_nb { int nb_id; /* NorthBridge id */ diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c index 980970c..ab91b11 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_ds.c +++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c @@ -714,6 +714,8 @@ void intel_pmu_pebs_enable(struct perf_event *event) struct hw_perf_event *hwc = &event->hw; hwc->config &= ~ARCH_PERFMON_EVENTSEL_INT; + if (!event->attr.freq) + hwc->flags |= PERF_X86_EVENT_AUTO_RELOAD; cpuc->pebs_enabled |= 1ULL << hwc->idx; @@ -721,6 +723,12 @@ void intel_pmu_pebs_enable(struct perf_event *event) cpuc->pebs_enabled |= 1ULL << (hwc->idx + 32); else if (event->hw.flags & PERF_X86_EVENT_PEBS_ST) cpuc->pebs_enabled |= 1ULL << 63; + + /* Use auto-reload if possible to save a MSR write in the PMI */ + if (hwc->flags & PERF_X86_EVENT_AUTO_RELOAD) { + ds->pebs_event_reset[hwc->idx] = + (u64)-hwc->sample_period & x86_pmu.cntval_mask; + } } void intel_pmu_pebs_disable(struct perf_event *event) @@ -739,6 +747,7 @@ void intel_pmu_pebs_disable(struct perf_event *event) wrmsrl(MSR_IA32_PEBS_ENABLE, cpuc->pebs_enabled); hwc->config |= ARCH_PERFMON_EVENTSEL_INT; + hwc->flags &= ~PERF_X86_EVENT_AUTO_RELOAD; } void intel_pmu_pebs_enable_all(void) -- 1.9.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/