Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758458Ab2F0Sfq (ORCPT ); Wed, 27 Jun 2012 14:35:46 -0400 Received: from e6.ny.us.ibm.com ([32.97.182.146]:43331 "EHLO e6.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756262Ab2F0Sfp (ORCPT ); Wed, 27 Jun 2012 14:35:45 -0400 Message-ID: <4FEB5267.8000109@linux.vnet.ibm.com> Date: Wed, 27 Jun 2012 13:35:19 -0500 From: Seth Jennings User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120615 Thunderbird/13.0.1 MIME-Version: 1.0 To: Konrad Rzeszutek Wilk CC: Dan Magenheimer , Minchan Kim , Alex Shi , Greg Kroah-Hartman , devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Robert Jennings , Nitin Gupta 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> <20120627153911.GH17154@phenom.dumpdata.com> In-Reply-To: <20120627153911.GH17154@phenom.dumpdata.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12062718-1976-0000-0000-00000E9F758F Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2042 Lines: 54 On 06/27/2012 10:39 AM, Konrad Rzeszutek Wilk wrote: > On Wed, Jun 27, 2012 at 08:12:56AM -0700, Dan Magenheimer wrote: >>> From: Minchan Kim [mailto:minchan@kernel.org] >>> Subject: Re: [PATCH 3/3] x86: add local_tlb_flush_kernel_range() >>> >>> Hello, >>> >>> On 06/27/2012 03:14 PM, Alex Shi wrote: >>> >>>> On 06/27/2012 01:53 PM, Minchan Kim wrote: >>>> >>>>> On 06/26/2012 01:14 AM, Seth Jennings wrote: >>>>> >>>>>> This patch adds support for a local_tlb_flush_kernel_range() >>>>>> function for the x86 arch. This function allows for CPU-local >>>>>> TLB flushing, potentially using invlpg for single entry flushing, >>>>>> using an arch independent function name. >>>>>> >>>>>> Signed-off-by: Seth Jennings >>>>> >>>>> >>>>> Anyway, we don't matter INVLPG_BREAK_EVEN_PAGES's optimization point is 8 or something. >>>> >>>> >>>> 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. > > At least put a big fat comment in the patch saying: > "This is based on research done by Alex, where ... I can do this. -- Seth -- 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/