From owner-freebsd-hackers@FreeBSD.ORG Fri Jul 12 14:01:08 2013 Return-Path: Delivered-To: hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id 17B8E21A for ; Fri, 12 Jul 2013 14:01:08 +0000 (UTC) (envelope-from carpeddiem@gmail.com) Received: from mail-qa0-x229.google.com (mail-qa0-x229.google.com [IPv6:2607:f8b0:400d:c00::229]) by mx1.freebsd.org (Postfix) with ESMTP id D2F2C1831 for ; Fri, 12 Jul 2013 14:01:07 +0000 (UTC) Received: by mail-qa0-f41.google.com with SMTP id f14so345153qak.14 for ; Fri, 12 Jul 2013 07:01:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; bh=6SGIF+3GSrn1IsUouWAQK/95Sg0EY9yyStvHi6dpK1g=; b=AhqVX4Tr5KDWhMOJGN2C79TFg4gLwbGmWTjfNxuEATjCQsLcZjr5Qa8d6FhwBMMHoD BH3LfYu+Csw1qjrsfGcdb4hvmmFGww4f2wAbzSe8U7cgEjHQ3bhiecDAAq4P6B0ioB/v gvQwbV/Ffr+iG4QqOMba9/llUektxfP8NkwUnNAs7g4uQBxPwRdDr3vcGMbOhWTeHgQ7 k+qRoreU0LUJallKMVULY4fKGXkb59+27qrYv8FLaginhEjtqQAs/r0TP50ZPNQhikEA nfh1lZMPa2zeZRQ8q49l0+TZNQFr9y7wJruxySXMo3tXBp6z3Wlaskc5Ul2Cq22R/rg8 zDcA== MIME-Version: 1.0 X-Received: by 10.229.134.2 with SMTP id h2mr6963130qct.94.1373637667445; Fri, 12 Jul 2013 07:01:07 -0700 (PDT) Sender: carpeddiem@gmail.com Received: by 10.224.209.6 with HTTP; Fri, 12 Jul 2013 07:01:07 -0700 (PDT) In-Reply-To: <51DDE91E.4000400@unsane.co.uk> References: <9890DFF1-892A-4DCA-9E33-B70681154F43@mail.turbofuzz.com> <4F0DFAB7-D6D5-4068-A543-C9DF885D1A7D@dragondata.com> <51DDE91E.4000400@unsane.co.uk> Date: Fri, 12 Jul 2013 10:01:07 -0400 X-Google-Sender-Auth: l8AkiZuHTcfYX7nG0VvkD0U59Gw Message-ID: Subject: Re: Kernel dumps [was Re: possible changes from Panzura] From: Ed Maste To: Vincent Hoffman Content-Type: text/plain; charset=ISO-8859-1 Cc: hackers@freebsd.org, Jordan Hubbard , Kevin Day X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 12 Jul 2013 14:01:08 -0000 On 10 July 2013 19:07, Vincent Hoffman wrote: > > There was some work on something similar at one point, not sure what > came of it. > http://lists.freebsd.org/pipermail/freebsd-current/2010-September/020164.html The code referenced there has been used in production since 2005 or so, and is based on an earlier implementation for FreeBSD 4.x that dates to 2000. Despite some shortcomings in the implementation it has proved quite reliable in practice. It hasn't made it into the tree yet for reasons raised in this thread. The primary issue is that it allocates mbufs in the packet sending path, and so relies on a number of kernel subsystems to be in a consistent state. It doesn't use the stack, routing table, or driver interrupt interfaces though. It could likely be made committable with a relatively small effort to switch to preallocating an mbuf+cluster or two at configuration time. More information is on the FreeBSD wiki, at https://wiki.freebsd.org/Netdump