Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757057AbZD2Kw2 (ORCPT ); Wed, 29 Apr 2009 06:52:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755274AbZD2KvI (ORCPT ); Wed, 29 Apr 2009 06:51:08 -0400 Received: from wa4ehsobe005.messaging.microsoft.com ([216.32.181.15]:23631 "EHLO WA4EHSOBE005.bigfish.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754860AbZD2KvB (ORCPT ); Wed, 29 Apr 2009 06:51:01 -0400 X-BigFish: VPS3(zzzz1202hzzz32i43j65h) X-Spam-TCS-SCL: 4:0 X-FB-SS: 5, X-WSS-ID: 0KIUZGO-02-18N-01 From: Robert Richter To: Peter Zijlstra CC: Paul Mackerras , Ingo Molnar , LKML , Robert Richter Subject: [PATCH 04/29] x86/perfcounters: rework pmc_amd_save_disable_all() and pmc_amd_restore_all() Date: Wed, 29 Apr 2009 12:47:01 +0200 Message-ID: <1241002046-8832-5-git-send-email-robert.richter@amd.com> X-Mailer: git-send-email 1.6.1.3 In-Reply-To: <1241002046-8832-1-git-send-email-robert.richter@amd.com> References: <1241002046-8832-1-git-send-email-robert.richter@amd.com> X-OriginalArrivalTime: 29 Apr 2009 10:50:49.0039 (UTC) FILETIME=[5B703DF0:01C9C8B8] MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1824 Lines: 61 MSR reads and writes are expensive. This patch adds checks to avoid its usage where possible. Signed-off-by: Robert Richter --- arch/x86/kernel/cpu/perf_counter.c | 24 ++++++++++++++---------- 1 files changed, 14 insertions(+), 10 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c index d6d6529..75a0903 100644 --- a/arch/x86/kernel/cpu/perf_counter.c +++ b/arch/x86/kernel/cpu/perf_counter.c @@ -334,11 +334,13 @@ static u64 pmc_amd_save_disable_all(void) for (idx = 0; idx < nr_counters_generic; idx++) { u64 val; + if (!test_bit(idx, cpuc->active_mask)) + continue; rdmsrl(MSR_K7_EVNTSEL0 + idx, val); - if (val & ARCH_PERFMON_EVENTSEL0_ENABLE) { - val &= ~ARCH_PERFMON_EVENTSEL0_ENABLE; - wrmsrl(MSR_K7_EVNTSEL0 + idx, val); - } + if (!(val & ARCH_PERFMON_EVENTSEL0_ENABLE)) + continue; + val &= ~ARCH_PERFMON_EVENTSEL0_ENABLE; + wrmsrl(MSR_K7_EVNTSEL0 + idx, val); } return enabled; @@ -372,13 +374,15 @@ static void pmc_amd_restore_all(u64 ctrl) return; for (idx = 0; idx < nr_counters_generic; idx++) { - if (test_bit(idx, cpuc->active_mask)) { - u64 val; + u64 val; - rdmsrl(MSR_K7_EVNTSEL0 + idx, val); - val |= ARCH_PERFMON_EVENTSEL0_ENABLE; - wrmsrl(MSR_K7_EVNTSEL0 + idx, val); - } + if (!test_bit(idx, cpuc->active_mask)) + continue; + rdmsrl(MSR_K7_EVNTSEL0 + idx, val); + if (val & ARCH_PERFMON_EVENTSEL0_ENABLE) + continue; + val |= ARCH_PERFMON_EVENTSEL0_ENABLE; + wrmsrl(MSR_K7_EVNTSEL0 + idx, val); } } -- 1.6.1.3 -- 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/