Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S270854AbTGVTix (ORCPT ); Tue, 22 Jul 2003 15:38:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S270860AbTGVTix (ORCPT ); Tue, 22 Jul 2003 15:38:53 -0400 Received: from turing-police.cc.vt.edu ([128.173.14.107]:19328 "EHLO turing-police.cc.vt.edu") by vger.kernel.org with ESMTP id S270854AbTGVTiv (ORCPT ); Tue, 22 Jul 2003 15:38:51 -0400 Message-Id: <200307221953.h6MJroXb001837@turing-police.cc.vt.edu> X-Mailer: exmh version 2.6.3 04/04/2003 with nmh-1.0.4+dev To: root@chaos.analogic.com Cc: Timothy Miller , Linux Kernel Mailing List Subject: Re: [ON TOPIC] HELP: Getting lousy memory throughput from Abit KD7 In-Reply-To: Your message of "Tue, 22 Jul 2003 15:34:51 EDT." From: Valdis.Kletnieks@vt.edu References: <3F1711B5.9020800@techsource.com> <3F1D8EAB.6020801@techsource.com> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_439975274P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Date: Tue, 22 Jul 2003 15:53:50 -0400 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1352 Lines: 39 --==_Exmh_439975274P Content-Type: text/plain; charset=us-ascii On Tue, 22 Jul 2003 15:34:51 EDT, "Richard B. Johnson" said: > If I needed to really find the memory access time, I would write > a program to test it. > (4) Warm the cache first by reading everything in the buffer you > are going to test. At which point you're measuring the cache speed not the memory speed. > You will probably be amazed at how well your system performs. This > dual CPU 400 MHz thing, with 100 MHz memory does 1,900++ MiB/sec. Which probably explains this result. Do a quick sanity check - this number seems to indicate 20 bytes per memory clock, EVERY clock - either there's some VERY creative use of prefetching to make sure that you never hit a cache line miss, or you're measuring the cache.. ;) --==_Exmh_439975274P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.2 (GNU/Linux) Comment: Exmh version 2.5 07/13/2001 iD8DBQE/HZZNcC3lWbTT17ARAlk6AJ9JZdkInkg6CCiX3NA0XcXqYM5mbwCfUaaG nNkE481Tl5/y60ofxUG961U= =pCb6 -----END PGP SIGNATURE----- --==_Exmh_439975274P-- - 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/