Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755341AbZGVNR5 (ORCPT ); Wed, 22 Jul 2009 09:17:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754011AbZGVNR5 (ORCPT ); Wed, 22 Jul 2009 09:17:57 -0400 Received: from wf-out-1314.google.com ([209.85.200.173]:11724 "EHLO wf-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753740AbZGVNR4 (ORCPT ); Wed, 22 Jul 2009 09:17:56 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=tj2O8OfsD8hXkK9SvNqPyDsuzWWipQ9CIATAoAeYyHfHXWMq6vDrq36+P9riUXHjnI 4CRzcf6sj+KjYD2+bnn8EmGROP3dlWi7bQ1PXPnkIxcdEfJRkUB1EiCwzaQ8drhX6eDL x7a4qhfYlqbCJ0nPdEBlUh71ABpDgbkSmW3V0= MIME-Version: 1.0 In-Reply-To: <1248267898.27058.1407.camel@twins> References: <1248267513-4934-1-git-send-email-tom.leiming@gmail.com> <1248267513-4934-2-git-send-email-tom.leiming@gmail.com> <1248267898.27058.1407.camel@twins> Date: Wed, 22 Jul 2009 21:17:56 +0800 Message-ID: Subject: Re: [tip:core/locking 1/3] lockdep:reintroduce generation count to make BFS faster From: Ming Lei To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, mingo@elte.hu, torvalds@linux-foundation.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1049 Lines: 34 2009/7/22 Peter Zijlstra : > On Wed, 2009-07-22 at 20:58 +0800, tom.leiming@gmail.com wrote: >> From: Ming Lei >> >> We still can apply DaveM's generation count optimization to >> BFS, so reintroduce it. > > Please elaborate, changelogs are important. Sorry, I'll resend the patches and provide a elaborate changlogs. > > You fail to explain why it still applies and what the gains are. > > (I can guess, but you explaining makes sure we're on the same page) > gains: 1), avoid to allocate the bfs_accessed array; 2), remove the bitmap_zero(bfs_accessed, MAX_LOCKDEP_ENTRIES); in each BFS, which is a little time consuming since MAX_LOCKDEP_ENTRIES is very large.(16384UL) -- Lei Ming -- 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/