From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261670AbVFKJ6n (ORCPT ); Sat, 11 Jun 2005 05:58:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261671AbVFKJ6m (ORCPT ); Sat, 11 Jun 2005 05:58:42 -0400 Received: from one.firstfloor.org ([213.235.205.2]:28832 "EHLO one.firstfloor.org") by vger.kernel.org with ESMTP id S261670AbVFKJ6l (ORCPT ); Sat, 11 Jun 2005 05:58:41 -0400 To: Subrahmanyam Ongole Cc: linux-kernel@vger.kernel.org Subject: Re: x86-64: Kernel with large page size References: From: Andi Kleen Date: Sat, 11 Jun 2005 11:58:39 +0200 In-Reply-To: (Subrahmanyam Ongole's message of "Fri, 3 Jun 2005 17:50:55 -0700") Message-ID: User-Agent: Gnus/5.110002 (No Gnus v0.2) Emacs/21.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Subrahmanyam Ongole writes: > When we run our application on AMD Opteron processors, we are seeing a > large number of L1_AND_L2_DTLB_MISSES. We used oprofile to measure > these numbers. > > We wanted to try with a bigger page size and see if we could bring it > down. TLB caches 4k page translations. I don't know if larger page You can use large pages in your application by mmaping from a file in hugetlbfs and configuring large pages using sysctl. > size would even help here. It probably wouldn't because Opteron has much more 4K DTLB entries than 2M DTLB entries. I have had people trying the opposite from what you tried (using 4K pages for the kernel instead of 2MB), but that also doesn't work right now. -Andi