From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx141.postini.com [74.125.245.141]) by kanga.kvack.org (Postfix) with SMTP id 4B4D96B005A for ; Wed, 27 Jun 2012 22:05:22 -0400 (EDT) Message-ID: <4FEBBB5C.5000505@intel.com> Date: Thu, 28 Jun 2012 10:03:08 +0800 From: Alex Shi MIME-Version: 1.0 Subject: Re: [PATCH 3/3] x86: add local_tlb_flush_kernel_range() References: <1340640878-27536-1-git-send-email-sjenning@linux.vnet.ibm.com> <1340640878-27536-4-git-send-email-sjenning@linux.vnet.ibm.com> <4FEA9FDD.6030102@kernel.org> <4FEAA4AA.3000406@intel.com> <4FEAA7A1.9020307@kernel.org> <90bcc2c8-bcac-4620-b3c0-6b65f8d9174d@default> <4FEB5204.3090707@linux.vnet.ibm.com> In-Reply-To: <4FEB5204.3090707@linux.vnet.ibm.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Seth Jennings Cc: Dan Magenheimer , Minchan Kim , Greg Kroah-Hartman , devel@driverdev.osuosl.org, Konrad Wilk , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Robert Jennings , Nitin Gupta , "H. Peter Anvin" On 06/28/2012 02:33 AM, Seth Jennings wrote: > On 06/27/2012 10:12 AM, Dan Magenheimer wrote: >>> From: Minchan Kim [mailto:minchan@kernel.org] >>> Subject: Re: [PATCH 3/3] x86: add local_tlb_flush_kernel_range() >>> >>> On 06/27/2012 03:14 PM, Alex Shi wrote: >>>> >>>> On 06/27/2012 01:53 PM, Minchan Kim wrote: >>>> Different CPU type has different balance point on the invlpg replacing >>>> flush all. and some CPU never get benefit from invlpg, So, it's better >>>> to use different value for different CPU, not a fixed >>>> INVLPG_BREAK_EVEN_PAGES. >>> >>> I think it could be another patch as further step and someone who are >>> very familiar with architecture could do better than. >>> So I hope it could be merged if it doesn't have real big problem. >>> >>> Thanks for the comment, Alex. >> >> Just my opinion, but I have to agree with Alex. Hardcoding >> behavior that is VERY processor-specific is a bad idea. TLBs should >> only be messed with when absolutely necessary, not for the >> convenience of defending an abstraction that is nice-to-have >> but, in current OS kernel code, unnecessary. > > I agree that it's not optimal. The selection based on CPUID > is part of Alex's patchset, and I'll be glad to use that > code when it gets integrated. > > But the real discussion is are we going to: > 1) wait until Alex's patches to be integrated, degrading > zsmalloc in the meantime or Peter Anvin is merging my TLB patch set into tip tree, x86/mm branch. > 2) put in some simple temporary logic that works well (not > best) for most cases -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org