From owner-freebsd-hackers Thu Apr 4 15:47:19 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from hawk.mail.pas.earthlink.net (hawk.mail.pas.earthlink.net [207.217.120.22]) by hub.freebsd.org (Postfix) with ESMTP id CF54937B405 for ; Thu, 4 Apr 2002 15:47:11 -0800 (PST) Received: from pool0517.cvx21-bradley.dialup.earthlink.net ([209.179.194.7] helo=mindspring.com) by hawk.mail.pas.earthlink.net with esmtp (Exim 3.33 #1) id 16tGwd-000547-00; Thu, 04 Apr 2002 15:47:07 -0800 Message-ID: <3CACE5E2.7C20E5BB@mindspring.com> Date: Thu, 04 Apr 2002 15:46:42 -0800 From: Terry Lambert X-Mailer: Mozilla 4.7 [en]C-CCK-MCD {Sony} (Win98; U) X-Accept-Language: en MIME-Version: 1.0 To: Andrew Gallatin Cc: Will Froning , hackers@freebsd.org Subject: Re: Fatal trap 12: page fault while in kernel mode References: <20020403181854.I42720-100000@angui.sh> <15532.29114.310072.957330@grasshopper.cs.duke.edu> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Andrew Gallatin wrote: > While the fix being discussed by Peter & others will prevent panics, > the linux box will still run your server out of mbufs clusters. This > is happening because the linux box is using a 16K write size over UDP > by default. This is a stupid default. If there is any lossage > between the hosts (eg, any packets get dropped), more and more packets > will end up on the reassembly queues. Eventually, all your cluster > mbufs will be there. > > I suggest changing the mount options on the linux box to use 8k reads > and writes, or use TCP. Good observation. Actually, for a firewall box, it might be reasonable to drop UDP packets over a certain size, and to drop certain classes of frags. This won't help the original poster with the Linux problem; they would still have to reconfigure their Linux machine to use smaller writes. > Another problem I've see w/Linux NFS clients is that recent linux NFS > clients seem to spew ACCESS requests like there's no tomorrow & beats > the snot out of my NFS server. When building large software pacakges > via "make -j4" over NFSv3 (100Mb ethernet) on a dual PIII 1GHz system, > a FreeBSD 4.5 host issues 400-500 ACCESS calls/sec. A Linux 2.4.18 > host spews 12,000 - 14,000 ACCESS calls/sec, or roughly 30 times as > many. Needless to say, the build finishes a whole lot quicker on > FreeBSD. Does anybody know what I can do to make the linux client > cache ACCESS info? Apart from installing FreeBSD instead? 8-). I think that it will take some hacking of the Linux NFS code by someone who cares about Linux performance. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message