From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751315AbWFBISG (ORCPT ); Fri, 2 Jun 2006 04:18:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751318AbWFBISG (ORCPT ); Fri, 2 Jun 2006 04:18:06 -0400 Received: from mail22.syd.optusnet.com.au ([211.29.133.160]:7847 "EHLO mail22.syd.optusnet.com.au") by vger.kernel.org with ESMTP id S1751315AbWFBISF (ORCPT ); Fri, 2 Jun 2006 04:18:05 -0400 From: Con Kolivas To: Nick Piggin Subject: Re: [PATCH RFC] smt nice introduces significant lock contention Date: Fri, 2 Jun 2006 18:17:46 +1000 User-Agent: KMail/1.9.1 Cc: linux-kernel@vger.kernel.org, "Chen, Kenneth W" , "'Chris Mason'" , Ingo Molnar References: <000101c685d7$1bc84390$d234030a@amr.corp.intel.com> <200606021608.33928.kernel@kolivas.org> <447FEE6C.7000408@yahoo.com.au> In-Reply-To: <447FEE6C.7000408@yahoo.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200606021817.46745.kernel@kolivas.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Friday 02 June 2006 17:53, Nick Piggin wrote: > This is a small micro-optimisation / cleanup we can do after > smtnice gets converted to use trylocks. Might result in a little > less cacheline footprint in some cases. It's only dependent_sleeper that is being converted in these patches. The wake_sleeping_dependent component still locks all runqueues and needs to succeed in order to ensure a task doesn't keep sleeping indefinitely. That one doesn't get called from schedule() so is far less expensive. This means I don't think we can change that cpu based locking order which I believe was introduce to prevent a deadlock (?DaveJ disovered it iirc). -- -ck