Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264646AbTFEMFR (ORCPT ); Thu, 5 Jun 2003 08:05:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264647AbTFEMFR (ORCPT ); Thu, 5 Jun 2003 08:05:17 -0400 Received: from users.linvision.com ([62.58.92.114]:45203 "EHLO abraracourcix.bitwizard.nl") by vger.kernel.org with ESMTP id S264646AbTFEMFM (ORCPT ); Thu, 5 Jun 2003 08:05:12 -0400 Date: Thu, 5 Jun 2003 14:18:40 +0200 From: Rogier Wolff To: linux-kernel@vger.kernel.org Subject: Fwd: Fwd: VFAT performance. Message-ID: <20030605141840.C22252@bitwizard.nl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.3.22.1i Organization: BitWizard.nl Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1707 Lines: 47 Hi, For the performance freaks: We're copying some data off a VFAT32 partition. We've opened the drive. (Yes I know, you're not supposed to do that. "Don't do this at home folks!" :-) When copying /dev/hda, we were able to achieve 11Mbyte per second: Our 100mpbs ethernet throughput. When copying large files off /mnt, we see a performance of about 7Mb per second. We see the head seek to the FAT about twice per second. This fits in with: 4K bytes of FAT contains 1024 fat entries. with a 4K clustersize, that would describe about 4Mbytes worth of data. So, at 7Mbytes per second we require a new FAT block twice per second. I think that we're loosing the 4Mbytes per second of performance due to the 4 seeks per second that the drive has to perform. The way to fix this would be to be able to assign a higher cache priority (*) to the blocks in the FAT, and to read more than just 4k per seek to the FAT. Just something to keep in mind when fiddling with the code again.... Roger. (*) i.e. expire them from the buffer cache less easily than normal blocks. -- ** R.E.Wolff@BitWizard.nl ** http://www.BitWizard.nl/ ** +31-15-2600998 ** *-- BitWizard writes Linux device drivers for any device you may have! --* * The Worlds Ecosystem is a stable system. Stable systems may experience * * excursions from the stable situation. We are currently in such an * * excursion: The stable situation does not include humans. *************** - 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/