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 S933309AbcFPCOy (ORCPT <rfc822;w@1wt.eu>);
	Wed, 15 Jun 2016 22:14:54 -0400
Received: from mx2.suse.de ([195.135.220.15]:36985 "EHLO mx2.suse.de"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1753345AbcFPCOv (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Wed, 15 Jun 2016 22:14:51 -0400
Date: Wed, 15 Jun 2016 19:14:36 -0700
From: Davidlohr Bueso <dave@stgolabs.net>
To: Waiman Long <waiman.long@hpe.com>
Cc: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>,
        linux-kernel@vger.kernel.org, x86@kernel.org,
        linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org,
        linux-s390@vger.kernel.org, linux-arch@vger.kernel.org,
        Jason Low <jason.low2@hp.com>, Dave Chinner <david@fromorbit.com>,
        Scott J Norton <scott.norton@hpe.com>,
        Douglas Hatch <doug.hatch@hpe.com>
Subject: Re: [RFC PATCH-tip v2 2/6] locking/rwsem: Stop active read lock ASAP
Message-ID: <20160616021436.GA7765@linux-80c1.suse>
References: <1465944489-43440-1-git-send-email-Waiman.Long@hpe.com>
 <1465944489-43440-3-git-send-email-Waiman.Long@hpe.com>
 <20160615172242.GQ30921@twins.programming.kicks-ass.net>
 <5761A9DE.6040702@hpe.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Disposition: inline
In-Reply-To: <5761A9DE.6040702@hpe.com>
User-Agent: Mutt/1.5.24 (2015-08-30)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Wed, 15 Jun 2016, Waiman Long wrote:

>I think there will be a little bit of performance impact for a 
>workload that produce just the right amount of rwsem contentions. 

I'm not saying the change doesn't make sense, but this is the sort of
thing that will show nice numbers in one workload and go bite you in
another.

Thanks,
Davidlohr

From mboxrd@z Thu Jan  1 00:00:00 1970
From: Davidlohr Bueso <dave@stgolabs.net>
Date: Thu, 16 Jun 2016 02:14:36 +0000
Subject: Re: [RFC PATCH-tip v2 2/6] locking/rwsem: Stop active read lock ASAP
Message-Id: <20160616021436.GA7765@linux-80c1.suse>
List-Id: <linux-ia64.vger.kernel.org>
References: <1465944489-43440-1-git-send-email-Waiman.Long@hpe.com>
 <1465944489-43440-3-git-send-email-Waiman.Long@hpe.com>
 <20160615172242.GQ30921@twins.programming.kicks-ass.net>
 <5761A9DE.6040702@hpe.com>
In-Reply-To: <5761A9DE.6040702@hpe.com>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
To: Waiman Long <waiman.long@hpe.com>
Cc: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org, x86@kernel.org, linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org, linux-s390@vger.kernel.org, linux-arch@vger.kernel.org, Jason Low <jason.low2@hp.com>, Dave Chinner <david@fromorbit.com>, Scott J Norton <scott.norton@hpe.com>, Douglas Hatch <doug.hatch@hpe.com>

On Wed, 15 Jun 2016, Waiman Long wrote:

>I think there will be a little bit of performance impact for a 
>workload that produce just the right amount of rwsem contentions. 

I'm not saying the change doesn't make sense, but this is the sort of
thing that will show nice numbers in one workload and go bite you in
another.

Thanks,
Davidlohr