From owner-svn-src-all@FreeBSD.ORG Fri Jun 11 16:12:10 2010 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 75D43106564A; Fri, 11 Jun 2010 16:12:10 +0000 (UTC) (envelope-from scottl@samsco.org) Received: from pooker.samsco.org (pooker.samsco.org [168.103.85.57]) by mx1.freebsd.org (Postfix) with ESMTP id 2B1ED8FC0A; Fri, 11 Jun 2010 16:12:09 +0000 (UTC) Received: from [127.0.0.1] (pooker.samsco.org [168.103.85.57]) (authenticated bits=0) by pooker.samsco.org (8.14.4/8.14.4) with ESMTP id o5BGC55k039477; Fri, 11 Jun 2010 10:12:06 -0600 (MDT) (envelope-from scottl@samsco.org) Mime-Version: 1.0 (Apple Message framework v1078) Content-Type: text/plain; charset=us-ascii From: Scott Long In-Reply-To: <201006110751.40735.jhb@freebsd.org> Date: Fri, 11 Jun 2010 10:12:05 -0600 Content-Transfer-Encoding: quoted-printable Message-Id: <853068F6-D736-4DA3-859F-D946D096843D@samsco.org> References: <201006110300.o5B30X9q045387@svn.freebsd.org> <201006110751.40735.jhb@freebsd.org> To: John Baldwin , Marcel Moolenaar X-Mailer: Apple Mail (2.1078) X-Spam-Status: No, score=-50.0 required=3.8 tests=ALL_TRUSTED, T_RP_MATCHES_RCVD autolearn=unavailable version=3.3.0 X-Spam-Checker-Version: SpamAssassin 3.3.0 (2010-01-18) on pooker.samsco.org Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r209026 - in head/sys/ia64: ia64 include X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 11 Jun 2010 16:12:10 -0000 On Jun 11, 2010, at 5:51 AM, John Baldwin wrote: > On Thursday 10 June 2010 11:00:33 pm Marcel Moolenaar wrote: >> Author: marcel >> Date: Fri Jun 11 03:00:32 2010 >> New Revision: 209026 >> URL: http://svn.freebsd.org/changeset/base/209026 >>=20 >> Log: >> Bump MAX_BPAGES from 256 to 1024. It seems that a few drivers, bge(4) >> in particular, do not handle deferred DMA map load operations at all. >> Any error, and especially EINPROGRESS, is treated as a hard error and >> typically abort the current operation. The fact that the busdma code >> queues the load operation for when resources (i.e. bounce buffers in >> this particular case) are available makes this especially = problematic. >> Bounce buffering, unlike what the PR synopsis would suggest, works >> fine. >>=20 >> While on the subject, properly implement swi_vm(). >=20 > NIC drivers do not handle deferred load operations at all (note that=20= > bus_dmamap_load_mbuf() and bus_dmamap_load_mbuf_sg() enforce = BUS_DMA_NOWAIT). > It is common practice to just drop the packet in that case. >=20 Yes, long ago when network drivers started being converted to busdma, it = was agreed that EINPROGRESS simply doesn't make sense for them. Any = platform that winds up making extensive use of bounce buffers for = network hardware is going to perform poorly no matter what, and should = hopefully have some sort of IOMMU that can be used instead. Scott