From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760893AbaGYTQn (ORCPT ); Fri, 25 Jul 2014 15:16:43 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:41386 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752893AbaGYTQm (ORCPT ); Fri, 25 Jul 2014 15:16:42 -0400 To: Christoph Hellwig Cc: James Bottomley , linux-scsi@vger.kernel.org, Jens Axboe , Bart Van Assche , Mike Christie , "Martin K. Petersen" , Robert Elliott , Webb Scales , linux-kernel@vger.kernel.org Subject: Re: [PATCH 12/14] scatterlist: allow chaining to preallocated chunks From: "Martin K. Petersen" Organization: Oracle Corporation References: <1405678393-11497-1-git-send-email-hch@lst.de> <1405678393-11497-13-git-send-email-hch@lst.de> Date: Fri, 25 Jul 2014 15:15:04 -0400 In-Reply-To: <1405678393-11497-13-git-send-email-hch@lst.de> (Christoph Hellwig's message of "Fri, 18 Jul 2014 12:13:11 +0200") Message-ID: User-Agent: Gnus/5.130012 (Ma Gnus v0.12) Emacs/24.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Source-IP: acsinet21.oracle.com [141.146.126.237] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>>>> "Christoph" == Christoph Hellwig writes: Christoph> Blk-mq drivers usually preallocate their S/G list as part of Christoph> the request, but if we want to support the very large S/G Christoph> lists currently supported by the SCSI code that would tie up Christoph> a lot of memory in the preallocated request pool. Add Christoph> support to the scatterlist code so that it can initialize a Christoph> S/G list that uses a preallocated first chunks and Christoph> dynamically allocated additional chunks. That way the Christoph> scsi-mq code can preallocate a first page worth of S/G Christoph> entries as part of the request, and dynamically extend the Christoph> S/G list when needed. Reviewed-by: Martin K. Petersen -- Martin K. Petersen Oracle Linux Engineering