Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754520AbZD2NF1 (ORCPT ); Wed, 29 Apr 2009 09:05:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757318AbZD2NEp (ORCPT ); Wed, 29 Apr 2009 09:04:45 -0400 Received: from hera.kernel.org ([140.211.167.34]:44512 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756852AbZD2NEn (ORCPT ); Wed, 29 Apr 2009 09:04:43 -0400 Date: Wed, 29 Apr 2009 13:04:05 GMT From: tip-bot for Robert Richter To: linux-tip-commits@vger.kernel.org Cc: linux-kernel@vger.kernel.org, paulus@samba.org, hpa@zytor.com, mingo@redhat.com, robert.richter@amd.com, a.p.zijlstra@chello.nl, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, paulus@samba.org, linux-kernel@vger.kernel.org, robert.richter@amd.com, a.p.zijlstra@chello.nl, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <1241002046-8832-5-git-send-email-robert.richter@amd.com> References: <1241002046-8832-5-git-send-email-robert.richter@amd.com> Subject: [tip:perfcounters/core] perf_counter, x86: rework pmc_amd_save_disable_all() and pmc_amd_restore_all() Message-ID: Git-Commit-ID: 4295ee62660b13ddb87d41539f49b239e6e7d56f X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Wed, 29 Apr 2009 13:04:07 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2454 Lines: 74 Commit-ID: 4295ee62660b13ddb87d41539f49b239e6e7d56f Gitweb: http://git.kernel.org/tip/4295ee62660b13ddb87d41539f49b239e6e7d56f Author: Robert Richter AuthorDate: Wed, 29 Apr 2009 12:47:01 +0200 Committer: Ingo Molnar CommitDate: Wed, 29 Apr 2009 14:51:02 +0200 perf_counter, x86: rework pmc_amd_save_disable_all() and pmc_amd_restore_all() MSR reads and writes are expensive. This patch adds checks to avoid its usage where possible. [ Impact: micro-optimization on AMD CPUs ] Signed-off-by: Robert Richter Cc: Paul Mackerras Acked-by: Peter Zijlstra LKML-Reference: <1241002046-8832-5-git-send-email-robert.richter@amd.com> Signed-off-by: Ingo Molnar --- 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); } } -- 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/