Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754097Ab3F0P7T (ORCPT ); Thu, 27 Jun 2013 11:59:19 -0400 Received: from mga09.intel.com ([134.134.136.24]:25885 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752648Ab3F0P7R (ORCPT ); Thu, 27 Jun 2013 11:59:17 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.87,953,1363158000"; d="scan'208";a="360554067" Subject: Re: [PATCH v4 1/5] rwsem: check the lock before cpmxchg in down_write_trylock From: Tim Chen To: Alex Shi Cc: Ingo Molnar , Andrew Morton , Andrea Arcangeli , Andi Kleen , Michel Lespinasse , Davidlohr Bueso , Matthew R Wilcox , Dave Hansen , Peter Zijlstra , Rik van Riel , Peter Hurley , linux-kernel@vger.kernel.org, linux-mm In-Reply-To: <51CB9631.1030508@intel.com> References: <1372285674.22432.141.camel@schen9-DESK> <51CB9631.1030508@intel.com> Content-Type: text/plain; charset="UTF-8" Date: Thu, 27 Jun 2013 08:59:18 -0700 Message-ID: <1372348758.22432.153.camel@schen9-DESK> Mime-Version: 1.0 X-Mailer: Evolution 2.32.3 (2.32.3-1.fc14) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 765 Lines: 25 On Thu, 2013-06-27 at 09:32 +0800, Alex Shi wrote: > The following line should be added head of commit log on patches 1~4. :) > > From: Alex Shi > > > > Cmpxchg will cause the cacheline bouning when do the value checking, > > that cause scalability issue in a large machine (like a 80 core box). > > > > So a lock pre-read can relief this contention. > > > > Signed-off-by: Alex Shi > > Okay. Will add the From line in addition to Signed off line on next update. Tim -- 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/