From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754725Ab1KRXkY (ORCPT ); Fri, 18 Nov 2011 18:40:24 -0500 Received: from terminus.zytor.com ([198.137.202.10]:53451 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751749Ab1KRXkW (ORCPT ); Fri, 18 Nov 2011 18:40:22 -0500 Date: Fri, 18 Nov 2011 15:39:55 -0800 From: tip-bot for Yong Zhang Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, a.p.zijlstra@chello.nl, mitake@dcl.info.waseda.ac.jp, yong.zhang0@gmail.com, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, mitake@dcl.info.waseda.ac.jp, tglx@linutronix.de, yong.zhang0@gmail.com, mingo@elte.hu In-Reply-To: <20111109080714.GC8124@zhy> References: <20111109080714.GC8124@zhy> To: linux-tip-commits@vger.kernel.org Subject: [tip:core/locking] lockdep: Always try to set ->class_cache in register_lock_class() lockdep_init_map() Git-Commit-ID: 87cdee71166fa107c5dc8e43060eeefa533c6a3b X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.6 (terminus.zytor.com [127.0.0.1]); Fri, 18 Nov 2011 15:40:05 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 87cdee71166fa107c5dc8e43060eeefa533c6a3b Gitweb: http://git.kernel.org/tip/87cdee71166fa107c5dc8e43060eeefa533c6a3b Author: Yong Zhang AuthorDate: Wed, 9 Nov 2011 16:07:14 +0800 Committer: Ingo Molnar CommitDate: Mon, 14 Nov 2011 13:54:11 +0100 lockdep: Always try to set ->class_cache in register_lock_class() lockdep_init_map() Commit ["62016250 lockdep: Add improved subclass caching"] tries to improve performance (expecially to reduce the cost of rq->lock) when using lockdep, but it fails due to lockdep_init_map() in which ->class_cache is cleared. The typical caller is lock_set_subclass(), after that class will not be cached anymore. This patch tries to achive the goal of commit 62016250 by always setting ->class_cache in register_lock_class(). === Score comparison of benchmarks === for i in `seq 1 10`; do ./perf bench -f simple sched messaging; done before: min: 0.604, max: 0.660, avg: 0.622 after: min: 0.414, max: 0.473, avg: 0.427 for i in `seq 1 10`; do ./perf bench -f simple sched messaging -g 40; done before: min: 2.347, max: 2.421, avg: 2.391 after: min: 1.652, max: 1.699, avg: 1.671 Signed-off-by: Yong Zhang Cc: Hitoshi Mitake Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20111109080714.GC8124@zhy Signed-off-by: Ingo Molnar --- kernel/lockdep.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/kernel/lockdep.c b/kernel/lockdep.c index e69434b..103bed8 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -722,7 +722,7 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) class = look_up_lock_class(lock, subclass); if (likely(class)) - return class; + goto out_set_class_cache; /* * Debug-check: all keys must be persistent! @@ -807,6 +807,7 @@ out_unlock_set: graph_unlock(); raw_local_irq_restore(flags); +out_set_class_cache: if (!subclass || force) lock->class_cache[0] = class; else if (subclass < NR_LOCKDEP_CACHING_CLASSES)