From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Staubach Subject: Re: NFS4 crack Date: Fri, 23 Sep 2005 08:17:28 -0400 Message-ID: <4333F258.1060603@redhat.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: akpm@osdl.org, andros@citi.umich.edu, bfields@citi.umich.edu, Christoph Hellwig , linux-fsdevel@vger.kernel.org, Neil Brown , Olaf Kirch , Trond Myklebust Return-path: Received: from mx1.redhat.com ([66.187.233.31]:50385 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S1750909AbVIWMSB (ORCPT ); Fri, 23 Sep 2005 08:18:01 -0400 To: Bryan Henderson In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Bryan Henderson wrote: > >It would be good to understand whether the NFS server is in the kernel for >basic structural reasons or just because we're too lazy to invent this new >system call interface, because that sheds light on how a normally user >space problem like storing persistent application data for NFSv4 should be >approached. Do we need a new kernel paradigm that admits file and >filename use within the kernel, or do we hold our nose and say, "what's >one more hack on top of an existing one?" > The NFS server is in the kernel for basic structural reasons, but also for performance reasons. I would be happy to hear and/or read a proposal on how to get packets containing requests and/or responses in and out of the kernel without copying them. Inside of the kernel, both can be handled with no copies. It isn't that we are too lazy, by the way. This issue gets looked into every so often. The set of system calls can be determined pretty quickly and implementing them, while tricky in spots, can be done. However, the ugliness of the implementation soon starts to overwhelm the cleanliness of the design. -- I would even be happy with seeing a user mode local disk based file system which performed as well as a kernel mode file system. That seems easier to to me because then there wouldn't be any of those sticky networking issues to worry about. When we get this, then we can consider the value of moving something like NFS too. Thanx... ps