From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932202Ab0CXQNm (ORCPT ); Wed, 24 Mar 2010 12:13:42 -0400 Received: from mga14.intel.com ([143.182.124.37]:17112 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932138Ab0CXQNk (ORCPT ); Wed, 24 Mar 2010 12:13:40 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.51,301,1267430400"; d="scan'208";a="258216815" Subject: Re: [patch 2/2] x86,pat Convert memtype_lock into an rw_lock. From: Suresh Siddha Reply-To: Suresh Siddha To: Peter Zijlstra Cc: "H. Peter Anvin" , "holt@sgi.com" , Ingo Molnar , Thomas Gleixner , Venkatesh Pallipadi , Linux Kernel Mailing List , "x86@kernel.org" In-Reply-To: <1269430347.5109.164.camel@twins> References: <1268871558.2696.60.camel@sbs-t61.fm.intel.com> <1269430347.5109.164.camel@twins> Content-Type: text/plain Organization: Intel Corp Date: Wed, 24 Mar 2010 09:12:26 -0700 Message-Id: <1269447146.2881.0.camel@sbs-t61.sc.intel.com> Mime-Version: 1.0 X-Mailer: Evolution 2.26.3 (2.26.3-1.fc11) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2010-03-24 at 04:32 -0700, Peter Zijlstra wrote: > On Wed, 2010-03-17 at 16:19 -0800, Suresh Siddha wrote: > > On Wed, 2010-03-17 at 12:51 -0700, H. Peter Anvin wrote: > > > Well, as you know :) tglx and I are on the road ... I'll try to get to it on Friday before I take off again. > > > > Also I talked to Thomas about this rwlock conversion and he referred to > > RT issues with rwlock. And the best is to avoid this using RCU. > > Its not just RT, even for mainline rwlock_t is a massive pain and often > is no better (actually worse) than a spinlock due to the massive > cacheline bouncing it introduces. Don't we have the same cacheline bouncing issues with the ticket spinlocks? thanks, suresh