Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753300Ab2HVKIC (ORCPT ); Wed, 22 Aug 2012 06:08:02 -0400 Received: from mail-we0-f174.google.com ([74.125.82.174]:54143 "EHLO mail-we0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750931Ab2HVKIA (ORCPT ); Wed, 22 Aug 2012 06:08:00 -0400 Date: Wed, 22 Aug 2012 12:07:55 +0200 From: Ingo Molnar To: Ido Yariv , "H. Peter Anvin" Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Shai Fultheim Subject: Re: [PATCH v2 2/2] x86/pat: Avoid contention on cpa_lock if possible Message-ID: <20120822100755.GA26323@gmail.com> References: <1344445299-22142-1-git-send-email-ido@wizery.com> <1344445299-22142-2-git-send-email-ido@wizery.com> <20120822084702.GA21764@gmail.com> <20120822095316.GA16110@WorkStation.localnet> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120822095316.GA16110@WorkStation.localnet> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2029 Lines: 55 * Ido Yariv wrote: > Hi Ingo, > > On Wed, Aug 22, 2012 at 10:47:02AM +0200, Ingo Molnar wrote: > > > > * Ido Yariv wrote: > > > > > vSMP Foundation does not require to serialize CPA by guaranteeing that > > > the most recent TLB entry will always be used. > > > > > > To avoid needless contention on cpa_lock, do not lock/unlock it if it > > > isn't necessary. > > > > > > Based on work by Shai Fultheim . > > > > > > Signed-off-by: Ido Yariv > > > Acked-by: Shai Fultheim > > > --- > > > Changes from v1: > > > - Use a synthetic CPUID bit and a use static_cpu_has() as suggested by > > > H. Peter Avnin > > > > > > arch/x86/include/asm/cpufeature.h | 1 + > > > arch/x86/kernel/vsmp_64.c | 10 ++++++++++ > > > arch/x86/mm/pageattr.c | 30 +++++++++++++++++++++--------- > > > 3 files changed, 32 insertions(+), 9 deletions(-) > > > > > > diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h > > > index 6b7ee5f..92303a0 100644 > > > --- a/arch/x86/include/asm/cpufeature.h > > > +++ b/arch/x86/include/asm/cpufeature.h > > > @@ -97,6 +97,7 @@ > > > #define X86_FEATURE_EXTD_APICID (3*32+26) /* has extended APICID (8 bits) */ > > > #define X86_FEATURE_AMD_DCM (3*32+27) /* multi-node processor */ > > > #define X86_FEATURE_APERFMPERF (3*32+28) /* APERFMPERF */ > > > +#define X86_FEATURE_NO_CPA_LOCK (3*32+29) /* Serializing cpa is not required */ > > > > Patch looks mostly good, but could we please use some more > > hardware-ish name, instead of referring to a kernel lock? > > Sure thing. How about X86_FEATURE_TLB_RELIABLE? Yeah, something like that. Maybe hpa can think of something better? Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/