From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964826AbWCHA1O (ORCPT ); Tue, 7 Mar 2006 19:27:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964835AbWCHA1N (ORCPT ); Tue, 7 Mar 2006 19:27:13 -0500 Received: from sabe.cs.wisc.edu ([128.105.6.20]:19623 "EHLO sabe.cs.wisc.edu") by vger.kernel.org with ESMTP id S964826AbWCHA1N (ORCPT ); Tue, 7 Mar 2006 19:27:13 -0500 Subject: [PATCH] update max_sectors documentation From: Mike Christie To: Jens Axboe , linux-kernel@vger.kernel.org Content-Type: text/plain Date: Tue, 07 Mar 2006 18:27:01 -0600 Message-Id: <1141777621.5594.3.camel@max> Mime-Version: 1.0 X-Mailer: Evolution 2.2.2 (2.2.2-5) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi Jens, I was looking over Kai's scsi command size email and was going to try and add it to some block docs and noticed I did not send the update to the max_sectors biodoc.txt. Sorry about that. Here is the patch against 2.6.16-rc5. The max_sectors has been split into max_hw_sectors and max_sectors for some time. A patch to have blk_queue_max_sectors enforce this was sent by me and it broke IDE. This patch updates the documentation. --- linux-2.6.16-rc5/Documentation/block/biodoc.txt 2006-02-26 23:09:35.000000000 -0600 +++ linux-2.6.16-rc5.work/Documentation/block/biodoc.txt 2006-03-07 18:10:57.000000000 -0600 @@ -132,8 +132,18 @@ Some new queue property settings: limit. No highmem default. blk_queue_max_sectors(q, max_sectors) - Maximum size request you can handle in units of 512 byte - sectors. 255 default. + Sets two variables that limit the size of the request. + + - The request queue's max_sectors, which is a soft size in + in units of 512 byte sectors, and could be dynamically varied + by the core kernel. + + - The request queue's max_hw_sectors, which is a hard limit + and reflects the maximum size request a driver can handle + in units of 512 byte sectors. + + The default for both max_sectors and max_hw_sectors is + 255. The upper limit of max_sectors is 1024. blk_queue_max_phys_segments(q, max_segments) Maximum physical segments you can handle in a request. 128