From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S969422AbdAEPaT (ORCPT <rfc822;w@1wt.eu>);
        Thu, 5 Jan 2017 10:30:19 -0500
Received: from mx1.redhat.com ([209.132.183.28]:41600 "EHLO mx1.redhat.com"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S969336AbdAEPaM (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Thu, 5 Jan 2017 10:30:12 -0500
Subject: Re: [PATCH v2] locking/pvqspinlock: Relax cmpxchg's to improve
 performance on some archs
To: Peter Zijlstra <peterz@infradead.org>
References: <1482697561-23848-1-git-send-email-longman@redhat.com>
 <20170103161836.GY3107@twins.programming.kicks-ass.net>
 <ada3bf4f-da8c-2ebf-15d8-f473ef1caf0c@redhat.com>
 <20170104094149.GD25813@worktop.programming.kicks-ass.net>
Cc: Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org,
        Pan Xinhui <xinhui@linux.vnet.ibm.com>,
        Boqun Feng <boqun.feng@gmail.com>
From: Waiman Long <longman@redhat.com>
Organization: Red Hat
Message-ID: <64289b85-8d10-e969-b05e-36184b6d8335@redhat.com>
Date: Thu, 5 Jan 2017 10:30:11 -0500
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101
 Thunderbird/45.4.0
MIME-Version: 1.0
In-Reply-To: <20170104094149.GD25813@worktop.programming.kicks-ass.net>
Content-Type: text/plain; charset=windows-1252
Content-Transfer-Encoding: 7bit
X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Thu, 05 Jan 2017 15:30:12 +0000 (UTC)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 01/04/2017 04:41 AM, Peter Zijlstra wrote:
> On Tue, Jan 03, 2017 at 05:07:54PM -0500, Waiman Long wrote:
>> On 01/03/2017 11:18 AM, Peter Zijlstra wrote:
>>> On Sun, Dec 25, 2016 at 03:26:01PM -0500, Waiman Long wrote:
>>>> A number of cmpxchg calls in qspinlock_paravirt.h were replaced by more
>>>> relaxed versions to improve performance on architectures that use LL/SC.
>>> Claim without numbers ;-)
>> Well it is hard to produce actual numbers here as I don't have the setup
>> to gather data.
> Surely RHT has big PPC machines around? I know that getting to them is a
> wee bit of a bother, but they should be available somewhere.

Yes, RHT does have PPC machines around. It is just I don't have
experience dealing with those machines yet. I will try to run some test
and include the numbers in the next version of the patch.

Cheers,
Longman