From mboxrd@z Thu Jan 1 00:00:00 1970 From: Waiman Long Subject: Re: [PATCH v8 10/10] pvqspinlock, x86: Enable qspinlock PV support for XEN Date: Wed, 02 Apr 2014 16:38:47 -0400 Message-ID: <533C7557.60908@hp.com> References: <1396445259-27670-1-git-send-email-Waiman.Long@hp.com> <1396445259-27670-11-git-send-email-Waiman.Long@hp.com> <20140402143932.GA13097@phenom.dumpdata.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140402143932.GA13097@phenom.dumpdata.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Konrad Rzeszutek Wilk Cc: linux-arch@vger.kernel.org, Raghavendra K T , Gleb Natapov , kvm@vger.kernel.org, Peter Zijlstra , Scott J Norton , x86@kernel.org, Paolo Bonzini , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Ingo Molnar , Chegu Vinod , David Vrabel , "H. Peter Anvin" , xen-devel@lists.xenproject.org, Thomas Gleixner , "Paul E. McKenney" , Linus Torvalds , Oleg Nesterov , Aswin Chandramouleeswaran List-Id: linux-arch.vger.kernel.org On 04/02/2014 10:39 AM, Konrad Rzeszutek Wilk wrote: >> diff --git a/kernel/Kconfig.locks b/kernel/Kconfig.locks >> index a70fdeb..451e392 100644 >> --- a/kernel/Kconfig.locks >> +++ b/kernel/Kconfig.locks >> @@ -229,4 +229,4 @@ config ARCH_USE_QUEUE_SPINLOCK >> >> config QUEUE_SPINLOCK >> def_bool y if ARCH_USE_QUEUE_SPINLOCK >> - depends on SMP&& (!PARAVIRT_SPINLOCKS || !XEN) >> + depends on SMP > If I read this correctly that means you cannot select any more the old > ticketlocks? As in, if you select CONFIG_PARAVIRT on X86 it will automatically > select ARCH_USE_QUEUE_SPINLOCK which will then enable this by default? > > Should the 'def_bool' be selectable? My initial qspinlock patch allows it to be selectable, but there was comment that doing so would increase the testing matrix and so made it less desirable. That was why I made it the default for 64-bit code which are more likely to be used in large machines which benefit the most from this patch. 32-bit kernel will still use the ticket lock. -Longman From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from g4t3426.houston.hp.com ([15.201.208.54]:19140 "EHLO g4t3426.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933194AbaDBUjK (ORCPT ); Wed, 2 Apr 2014 16:39:10 -0400 Message-ID: <533C7557.60908@hp.com> Date: Wed, 02 Apr 2014 16:38:47 -0400 From: Waiman Long MIME-Version: 1.0 Subject: Re: [PATCH v8 10/10] pvqspinlock, x86: Enable qspinlock PV support for XEN References: <1396445259-27670-1-git-send-email-Waiman.Long@hp.com> <1396445259-27670-11-git-send-email-Waiman.Long@hp.com> <20140402143932.GA13097@phenom.dumpdata.com> In-Reply-To: <20140402143932.GA13097@phenom.dumpdata.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: Konrad Rzeszutek Wilk Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Peter Zijlstra , linux-arch@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, xen-devel@lists.xenproject.org, kvm@vger.kernel.org, Paolo Bonzini , "Paul E. McKenney" , Rik van Riel , Linus Torvalds , Raghavendra K T , David Vrabel , Oleg Nesterov , Gleb Natapov , Aswin Chandramouleeswaran , Scott J Norton , Chegu Vinod Message-ID: <20140402203847.dKlPM3WLJUe35ZyCihVvsP4IW7XpUxgmh_imVm5MK7I@z> On 04/02/2014 10:39 AM, Konrad Rzeszutek Wilk wrote: >> diff --git a/kernel/Kconfig.locks b/kernel/Kconfig.locks >> index a70fdeb..451e392 100644 >> --- a/kernel/Kconfig.locks >> +++ b/kernel/Kconfig.locks >> @@ -229,4 +229,4 @@ config ARCH_USE_QUEUE_SPINLOCK >> >> config QUEUE_SPINLOCK >> def_bool y if ARCH_USE_QUEUE_SPINLOCK >> - depends on SMP&& (!PARAVIRT_SPINLOCKS || !XEN) >> + depends on SMP > If I read this correctly that means you cannot select any more the old > ticketlocks? As in, if you select CONFIG_PARAVIRT on X86 it will automatically > select ARCH_USE_QUEUE_SPINLOCK which will then enable this by default? > > Should the 'def_bool' be selectable? My initial qspinlock patch allows it to be selectable, but there was comment that doing so would increase the testing matrix and so made it less desirable. That was why I made it the default for 64-bit code which are more likely to be used in large machines which benefit the most from this patch. 32-bit kernel will still use the ticket lock. -Longman