Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 30 Jul 2001 19:33:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 30 Jul 2001 19:33:30 -0400 Received: from ns1.austin.rr.com ([24.93.35.62]:24581 "EHLO ns1.austin.rr.com") by vger.kernel.org with ESMTP id ; Mon, 30 Jul 2001 19:33:17 -0400 Content-Type: text/plain; charset=US-ASCII From: Marvin Justice Reply-To: mjustice@austin.rr.com To: linux-kernel@vger.kernel.org Subject: Serverworks LE, 4GB RAM, and MTRR Date: Mon, 30 Jul 2001 18:37:02 -0500 X-Mailer: KMail [version 1.2] MIME-Version: 1.0 Message-Id: <01073018370207.04012@bozo> Content-Transfer-Encoding: 7BIT Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Original-Recipient: rfc822;linux-kernel-outgoing Slow performance on Serverworks LE boards with 4GB of RAM seem to be related to mtrr misconfiguration. Here is the /proc/mtrr for a Tyan 2510 ( 2.4.7-ac2): reg00: base=0x00000000 ( 0MB), size=2048MB: write-back, count=1 reg01: base=0x80000000 (2048MB), size=1024MB: write-back, count=1 reg02: base=0xc0000000 (3072MB), size= 512MB: write-back, count=1 reg03: base=0xe0000000 (3584MB), size= 256MB: write-back, count=1 reg04: base=0xf0000000 (3840MB), size= 128MB: write-back, count=1 reg05: base=0xf8000000 (3968MB), size= 64MB: write-back, count=1 reg06: base=0xfc000000 (4032MB), size= 64MB: uncachable, count=1 Also, the framebuffer is 4MB starting at 0xfd000000 (4048MB) on this system. The last entry seems to be the culprit. Why should there be 64MB uncachable starting at 4032? Back in April there was a thread concering the mtrr setup for the LE chipset. A patch for mtrr.c was submitted (but never accepted, apparently) that allows write-combining (which is currently disabled for all Serverworks LE) for revisions >5. If I modify mtrr.c to allow write-combining the system works normally with 4G. /proc/mtrr is unchanged but the following line shows up in the syslog when the X-server is started: mtrr: type mismatch for fd000000,400000 old: uncachable new: write-combining The slowness of the system without write-combining is independent of whether X is started. Marvin Justice - 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/