From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265733AbTGDCej (ORCPT ); Thu, 3 Jul 2003 22:34:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265659AbTGDCdn (ORCPT ); Thu, 3 Jul 2003 22:33:43 -0400 Received: from franka.aracnet.com ([216.99.193.44]:57799 "EHLO franka.aracnet.com") by vger.kernel.org with ESMTP id S265751AbTGDCcQ (ORCPT ); Thu, 3 Jul 2003 22:32:16 -0400 Date: Thu, 03 Jul 2003 19:46:24 -0700 From: "Martin J. Bligh" To: Dave Hansen cc: linux-kernel , Andrew Morton , William Lee Irwin III Subject: Re: Overhead of highpte Message-ID: <68160000.1057286782@[10.10.2.4]> In-Reply-To: <1057286058.11027.106.camel@nighthawk> References: <574790000.1057186404@flay> <1057286058.11027.106.camel@nighthawk> X-Mailer: Mulberry/2.2.1 (Linux/x86) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > On Wed, 2003-07-02 at 15:53, Martin J. Bligh wrote: >> Some people were saying they couldn't see an overhead with highpte. >> Seems pretty obvious to me still. It should help *more* on the NUMA >> box, as PTEs become node-local. >> >> The kmap_atomic is, of course, perfectly understandable. The increase >> in the rmap functions is a bit of a mystery to me. >> >> M. >> >> Kernbench: (make -j vmlinux, maximal tasks) >> Elapsed System User CPU >> 2.5.73-mm3 45.38 114.91 565.81 1497.75 >> 2.5.73-mm3-highpte 46.54 130.41 566.84 1498.00 > > OK, let's add to the mystery. Here's my run, on virtually the same > hardware except, I don't do a bzImage. bzImage is pretty useless > because I don't want to benchmark gzip, so I just do vmlinux. My times > should be _faster_ than yours, right? I do vmlinux as well. > Elapsed: User: System: CPU: > 2.5.73-mjb2 77.008s 937.756s 90s 1334% > 2.5.73-mjb2-highpte 76.756s 935.464s 93.116s 1339% > > Yeah, system time goes up. Something funky is going on. We should have > the same machines, except that I have twice the RAM, right? What kind > of fs are you doing your tests on? I'm doing ramfs. ext2. I suspect the problem is that your gcc is such a slow piece of shit, you're totally userspace bound. Try 2.95 (just move the /usr/bin/gcc symlink on debian). M.