Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762208AbYGOClq (ORCPT ); Mon, 14 Jul 2008 22:41:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759534AbYGOClW (ORCPT ); Mon, 14 Jul 2008 22:41:22 -0400 Received: from sh.osrg.net ([192.16.179.4]:44245 "EHLO sh.osrg.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762251AbYGOClV (ORCPT ); Mon, 14 Jul 2008 22:41:21 -0400 Date: Tue, 15 Jul 2008 11:40:45 +0900 To: mpatocka@redhat.com Cc: davem@davemloft.net, 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: FUJITA Tomonori In-Reply-To: References: <20080714.052859.88212003.davem@davemloft.net> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-Id: <20080715113238U.fujita.tomonori@lab.ntt.co.jp> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1090 Lines: 21 On Mon, 14 Jul 2008 10:03:29 -0400 (EDT) Mikulas Patocka wrote: > On Mon, 14 Jul 2008, David Miller wrote: > > > 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. > > Why would someone want to overshoot SG_ALL? ... and, shouldn't the > constant be increased then --- instead of making buggy BIO_VMERGE_BOUNDARY > expectations? 'buggy' is a wrong word. VMERGE works for some IOMMUs (though I think that we need to fix it about max_segment_size). -- 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/