Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755206AbZKUNl7 (ORCPT ); Sat, 21 Nov 2009 08:41:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755011AbZKUNl5 (ORCPT ); Sat, 21 Nov 2009 08:41:57 -0500 Received: from hera.kernel.org ([140.211.167.34]:60850 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755155AbZKUNlz (ORCPT ); Sat, 21 Nov 2009 08:41:55 -0500 Date: Sat, 21 Nov 2009 13:41:29 GMT From: tip-bot for Peter Zijlstra Cc: linux-kernel@vger.kernel.org, paulus@samba.org, hpa@zytor.com, mingo@redhat.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, a.p.zijlstra@chello.nl, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <20091120212508.378188589@chello.nl> References: <20091120212508.378188589@chello.nl> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/core] perf: Optimize perf_swevent_ctx_event() Message-ID: Git-Commit-ID: 81520183878a8813c71c9372de28bb70913ba549 X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2264 Lines: 65 Commit-ID: 81520183878a8813c71c9372de28bb70913ba549 Gitweb: http://git.kernel.org/tip/81520183878a8813c71c9372de28bb70913ba549 Author: Peter Zijlstra AuthorDate: Fri, 20 Nov 2009 22:19:45 +0100 Committer: Ingo Molnar CommitDate: Sat, 21 Nov 2009 14:11:35 +0100 perf: Optimize perf_swevent_ctx_event() Remove a rcu_read_{,un}lock() pair and a few conditionals. We can remove the rcu_read_lock() by increasing the scope of one in the calling function. We can do away with the system_state check if the machine still boots after this patch (seems to be the case). We can do away with the list_empty() check because the bare list_for_each_entry_rcu() reduces to that now that we've removed everything else. Signed-off-by: Peter Zijlstra Cc: Paul Mackerras LKML-Reference: <20091120212508.378188589@chello.nl> Signed-off-by: Ingo Molnar --- kernel/perf_event.c | 7 +------ 1 files changed, 1 insertions(+), 6 deletions(-) diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 8e55b44..cda17ac 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -3886,15 +3886,10 @@ static void perf_swevent_ctx_event(struct perf_event_context *ctx, { struct perf_event *event; - if (system_state != SYSTEM_RUNNING || list_empty(&ctx->event_list)) - return; - - rcu_read_lock(); list_for_each_entry_rcu(event, &ctx->event_list, event_entry) { if (perf_swevent_match(event, type, event_id, data, regs)) perf_swevent_add(event, nr, nmi, data, regs); } - rcu_read_unlock(); } static int *perf_swevent_recursion_context(struct perf_cpu_context *cpuctx) @@ -3926,9 +3921,9 @@ static void do_perf_sw_event(enum perf_type_id type, u32 event_id, (*recursion)++; barrier(); + rcu_read_lock(); perf_swevent_ctx_event(&cpuctx->ctx, type, event_id, nr, nmi, data, regs); - rcu_read_lock(); /* * doesn't really matter which of the child contexts the * events ends up in. -- 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/