From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753128AbcDMPxo (ORCPT ); Wed, 13 Apr 2016 11:53:44 -0400 Received: from mail-bn1on0133.outbound.protection.outlook.com ([157.56.110.133]:52390 "EHLO na01-bn1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752696AbcDMPxn (ORCPT ); Wed, 13 Apr 2016 11:53:43 -0400 Authentication-Results: linux.vnet.ibm.com; dkim=none (message not signed) header.d=none;linux.vnet.ibm.com; dmarc=none action=none header.from=hpe.com; Message-ID: <570E6B76.5080306@hpe.com> Date: Wed, 13 Apr 2016 11:53:26 -0400 From: Waiman Long User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.12) Gecko/20130109 Thunderbird/10.0.12 MIME-Version: 1.0 To: Pan Xinhui CC: Peter Zijlstra , , , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Boqun Feng , Thomas Gleixner Subject: Re: [PATCH] powerpc: introduce {cmp}xchg for u8 and u16 References: <570752AA.9050603@linux.vnet.ibm.com> <20160408074744.GU3430@twins.programming.kicks-ass.net> <570A6078.2050002@linux.vnet.ibm.com> <20160412143023.GH1087@worktop> <570E2A45.9080702@linux.vnet.ibm.com> In-Reply-To: <570E2A45.9080702@linux.vnet.ibm.com> Content-Type: text/plain; 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I am preparing the patches and will send them out in next weeks :) What of performance improvement are you seeing in PPC? > The paravirt work is a little hard. > currently, there are pv_wait() and pv_kick(). but only pv_kick has the parameter cpu(who will hold the lock as soon as the lock is unlocked). > We need parameter cpu(who holds the lock now) in pv_wait,too. That can be doable to a certain extent. However, if the current lock holder acquired the lock via the fastpath only. The CPU information is not logged anywhere. For a contended lock, the information should be there. Cheers, Longman