From mboxrd@z Thu Jan 1 00:00:00 1970 From: Raghavendra K T Subject: Re: [PATCH RFC 1/2] qspinlock: Introducing a 4-byte queue spinlock implementation Date: Fri, 02 Aug 2013 08:30:32 +0530 Message-ID: <51FB20D0.5070306@linux.vnet.ibm.com> References: <1375324631-32868-1-git-send-email-Waiman.Long@hp.com> <1375324631-32868-2-git-send-email-Waiman.Long@hp.com> <51FAC3BA.9050705@linux.vnet.ibm.com> <51FACE78.9070901@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from e23smtp03.au.ibm.com ([202.81.31.145]:58715 "EHLO e23smtp03.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752649Ab3HBCyZ (ORCPT ); Thu, 1 Aug 2013 22:54:25 -0400 Received: from /spool/local by e23smtp03.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 2 Aug 2013 12:43:52 +1000 In-Reply-To: <51FACE78.9070901@hp.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Waiman Long Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Arnd Bergmann , linux-arch@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, Peter Zijlstra , Steven Rostedt , Andrew Morton , Richard Weinberger , Catalin Marinas , Greg Kroah-Hartman , Matt Fleming , Herbert Xu , Akinobu Mita , Rusty Russell , Michel Lespinasse , Andi Kleen , Rik van Riel , "Paul E. McKenney" , Linus Torvalds , George Spelvin Harvey Harrison On 08/02/2013 02:39 AM, Waiman Long wrote: > On 08/01/2013 04:23 PM, Raghavendra K T wrote: >> On 08/01/2013 08:07 AM, Waiman Long wrote: [..] >> >> Though I could see some gains in overcommit, but it hurted undercommit >> in some workloads :(. > > The gcc 4.4.7 compiler that I used in my test machine has the tendency > of allocating stack space for variables instead of using registers when > a loop is present. So I try to avoid having loop in the fast path. Also > the count itself is rather arbitrary. For the first pass, I would like > to make thing simple. We can always enhance it once it is accepted and > merged. Yes. agree. >> >> I have not yet tested on bigger machine. I hope that bigger machine will >> see significant undercommit improvements. >> > > Thank for running the test. I am a bit confused about the terminology. > What exactly do undercommit and overcommit mean? > Undercommit means I meant total #vcpu < #pcpus in virtual env. so overcommit should not be an issue in baremetal. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp03.au.ibm.com ([202.81.31.145]:58715 "EHLO e23smtp03.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752649Ab3HBCyZ (ORCPT ); Thu, 1 Aug 2013 22:54:25 -0400 Received: from /spool/local by e23smtp03.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 2 Aug 2013 12:43:52 +1000 Message-ID: <51FB20D0.5070306@linux.vnet.ibm.com> Date: Fri, 02 Aug 2013 08:30:32 +0530 From: Raghavendra K T MIME-Version: 1.0 Subject: Re: [PATCH RFC 1/2] qspinlock: Introducing a 4-byte queue spinlock implementation References: <1375324631-32868-1-git-send-email-Waiman.Long@hp.com> <1375324631-32868-2-git-send-email-Waiman.Long@hp.com> <51FAC3BA.9050705@linux.vnet.ibm.com> <51FACE78.9070901@hp.com> In-Reply-To: <51FACE78.9070901@hp.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Waiman Long Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Arnd Bergmann , linux-arch@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, Peter Zijlstra , Steven Rostedt , Andrew Morton , Richard Weinberger , Catalin Marinas , Greg Kroah-Hartman , Matt Fleming , Herbert Xu , Akinobu Mita , Rusty Russell , Michel Lespinasse , Andi Kleen , Rik van Riel , "Paul E. McKenney" , Linus Torvalds , George Spelvin , Harvey Harrison , "Chandramouleeswaran, Aswin" , "Norton, Scott J" Message-ID: <20130802030032.8fhKqEteu0MImYH0k0CykxUsrONDi9431uz-C8m8NT4@z> On 08/02/2013 02:39 AM, Waiman Long wrote: > On 08/01/2013 04:23 PM, Raghavendra K T wrote: >> On 08/01/2013 08:07 AM, Waiman Long wrote: [..] >> >> Though I could see some gains in overcommit, but it hurted undercommit >> in some workloads :(. > > The gcc 4.4.7 compiler that I used in my test machine has the tendency > of allocating stack space for variables instead of using registers when > a loop is present. So I try to avoid having loop in the fast path. Also > the count itself is rather arbitrary. For the first pass, I would like > to make thing simple. We can always enhance it once it is accepted and > merged. Yes. agree. >> >> I have not yet tested on bigger machine. I hope that bigger machine will >> see significant undercommit improvements. >> > > Thank for running the test. I am a bit confused about the terminology. > What exactly do undercommit and overcommit mean? > Undercommit means I meant total #vcpu < #pcpus in virtual env. so overcommit should not be an issue in baremetal.