From owner-freebsd-stable@FreeBSD.ORG Wed Aug 9 09:02:52 2006 Return-Path: X-Original-To: stable@freebsd.org Delivered-To: freebsd-stable@FreeBSD.ORG Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 3215216A4DD for ; Wed, 9 Aug 2006 09:02:52 +0000 (UTC) (envelope-from scott.wilson@gmail.com) Received: from nf-out-0910.google.com (nf-out-0910.google.com [64.233.182.187]) by mx1.FreeBSD.org (Postfix) with ESMTP id 5883143D73 for ; Wed, 9 Aug 2006 09:02:44 +0000 (GMT) (envelope-from scott.wilson@gmail.com) Received: by nf-out-0910.google.com with SMTP id g2so99257nfe for ; Wed, 09 Aug 2006 02:02:37 -0700 (PDT) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=JirNvsiobV+vCOkKhrKtSzEgkajgZVl0H2GCGBNN+tkzx4F8YdKLVMflTY1m3fvTs8CmMnxyne+P++zf9G3cKN6qMSL9OJFl+gzQKR3prLTzkZnz+dIHudH4DL3XfLWnxzZtCnxihudzusmjCJR2btDaWJDf4rnhA56zYODTdEA= Received: by 10.78.116.19 with SMTP id o19mr227333huc; Wed, 09 Aug 2006 02:02:37 -0700 (PDT) Received: by 10.78.70.10 with HTTP; Wed, 9 Aug 2006 02:02:37 -0700 (PDT) Message-ID: Date: Wed, 9 Aug 2006 11:02:37 +0200 From: "Scott Wilson" To: "David (Controller AE) Christensen" In-Reply-To: <09BFF2FA5EAB4A45B6655E151BBDD90301AB72BF@NT-IRVA-0750.brcm.ad.broadcom.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20060808003404.GA5411@cdnetworks.co.kr> <09BFF2FA5EAB4A45B6655E151BBDD90301AB72BF@NT-IRVA-0750.brcm.ad.broadcom.com> Cc: pyunyh@gmail.com, stable@freebsd.org, davidch@freebsd.org, Eric Hodel Subject: Re: RE: Re: Re: bce0: Error mapping mbuf into TX chain! X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 09 Aug 2006 09:02:52 -0000 On 8/8/06, David (Controller AE) Christensen wrote: > > > > Since BCE_MAX_SEGMENTS is too small I guess it will happen on highly > > fragmented packets under heavy loads. To simulate the situation > > you can use m_fragment(9) to fragment the frame in bce_tx_encap(). > > With m_fragment(9), "ping -f -s 65507 x.x.x.x" may trigger it. > > > > I didn't know about m_fragment before. I'll write a note to myself > and look at how to add it to the debug path for a future driver > revision. > > > Btw, I've never seen this small number of Tx DMA segments support( > > BCE_MAX_SEGMENTS == 8) on GigE. Is this hardware limitation? > > > > The real value for BCE_MAX_SEGMENTS should be 16, not 8. I chose 8 as a > reasonable value to start with. If the number of fragments exceeds 16 > then we would expect to see performance drop and it is probably faster > to > have the OS defragment the packet rather than try to perform so many > DMAs. > What I don't understand is why the driver stays locked up after it gets into this mode. I guess that's a separate issue from the low max segments which is triggering it in the first place? -scott