From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 18 Jan 2001 19:16:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 18 Jan 2001 19:16:14 -0500 Received: from penguin.e-mind.com ([195.223.140.120]:22394 "EHLO penguin.e-mind.com") by vger.kernel.org with ESMTP id ; Thu, 18 Jan 2001 19:16:04 -0500 Date: Fri, 19 Jan 2001 01:16:29 +0100 From: Andrea Arcangeli To: Marcelo Tosatti Cc: Jens Axboe , linux-kernel@vger.kernel.org Subject: Re: 2.4.1pre8 slowdown on dbench tests Message-ID: <20010119011629.C32087@athlon.random> In-Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ; from marcelo@conectiva.com.br on Thu, Jan 18, 2001 at 03:17:13PM -0200 X-GnuPG-Key-URL: http://e-mind.com/~andrea/aa.gnupg.asc X-PGP-Key-URL: http://e-mind.com/~andrea/aa.asc Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 18, 2001 at 03:17:13PM -0200, Marcelo Tosatti wrote: > Jens, can be the -blk patch the reason for the slowdown I'm seeing? This heuristic is way too aggressive: /* * Try to keep 128MB max hysteris. If not possible, * use half of RAM */ high_queued_sectors = (total_ram * 2) / 3; low_queued_sectors = high_queued_sectors - MB(128); if (low_queued_sectors < 0) low_queued_sectors = total_ram / 2; /* * for big RAM machines (>= 384MB), use more for I/O */ if (total_ram >= MB(384)) { high_queued_sectors = (total_ram * 4) / 5; low_queued_sectors = high_queued_sectors - MB(128); } 2/3 of ram locked down in the I/O queue is way too much. 1/3 should be ok. big RAM machines needs way less than 1/3 locked down. Marcelo can you give a try with `high_queued_sectors = total_ram / 3' and low_queued_sectors = high_queued_sectors / 2 and drop the big ram machine check? Andrea - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/