Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754196AbYGNM3P (ORCPT ); Mon, 14 Jul 2008 08:29:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751614AbYGNM27 (ORCPT ); Mon, 14 Jul 2008 08:28:59 -0400 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:55796 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751381AbYGNM26 (ORCPT ); Mon, 14 Jul 2008 08:28:58 -0400 Date: Mon, 14 Jul 2008 05:28:59 -0700 (PDT) Message-Id: <20080714.052859.88212003.davem@davemloft.net> To: mpatocka@redhat.com Cc: andi@firstfloor.org, sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org, jens.axboe@oracle.com Subject: Re: [SUGGESTION]: drop virtual merge accounting in I/O requests From: David Miller In-Reply-To: References: <20080713.174855.234796356.davem@davemloft.net> X-Mailer: Mew version 5.2 on Emacs 22.1 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 731 Lines: 17 From: Mikulas Patocka Date: Mon, 14 Jul 2008 08:16:13 -0400 (EDT) > As you mentioned ESP driver, it declares .sg_tablesize = SG_ALL, so > BIO_VMERGE_BOUNDARY has no effect on the operation of this driver. Any > other driver where BIO_VMERGE_BOUNDARY does matter? When BIO_VMERGE_BOUNDARY is turned on, requests that would not otherwise fit into the device's limits, can. It's the only way to know ahead of time that the IOMMU is going to merge things for us. -- 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/