From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Martin K. Petersen" Subject: Re: How to make kernel block layer generate bigger request in the request queue? Date: Fri, 09 Apr 2010 22:05:50 -0400 Message-ID: References: <4BBFBE3E.5070605@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from rcsinet12.oracle.com ([148.87.113.124]:51075 "EHLO rcsinet12.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751487Ab0DJCGO (ORCPT ); Fri, 9 Apr 2010 22:06:14 -0400 In-Reply-To: <4BBFBE3E.5070605@gmail.com> (Robert Hancock's message of "Fri, 09 Apr 2010 17:54:38 -0600") Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Robert Hancock Cc: "Gao, Yunpeng" , "linux-ide@vger.kernel.org" , "linux-mmc@vger.kernel.org" >>>>> "Robert" == Robert Hancock writes: >> Did I miss something to make the block layer generate bigger size >> data for every request in the request queue? Below is part of my >> source code. Any comments are highly appreciated. Thank you in >> advance. Robert> 8 sectors is 4KB, that's the size of a page. If the pages that Robert> are being written are not physically contiguous that may be the Robert> best the block layer can do with the constraints you've given it Robert> (not supporting any more than 1 DMA segment). Correct. It's quite unlikely for pages to be contiguous so this is the best we can do. Having recently done a cleanup of our segment handling I became aware that there are many MMC devices that are single-element only. This was probably a sufficient approach for 32MB devices but it's time to get with the program and implement proper scatter-gather. -- Martin K. Petersen Oracle Linux Engineering