From owner-freebsd-current@FreeBSD.ORG Thu Sep 30 21:44:15 2010 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 3081A106564A for ; Thu, 30 Sep 2010 21:44:15 +0000 (UTC) (envelope-from andre@freebsd.org) Received: from c00l3r.networx.ch (c00l3r.networx.ch [62.48.2.2]) by mx1.freebsd.org (Postfix) with ESMTP id 949F28FC25 for ; Thu, 30 Sep 2010 21:44:14 +0000 (UTC) Received: (qmail 22636 invoked from network); 30 Sep 2010 21:36:09 -0000 Received: from localhost (HELO [127.0.0.1]) ([127.0.0.1]) (envelope-sender ) by c00l3r.networx.ch (qmail-ldap-1.03) with SMTP for ; 30 Sep 2010 21:36:09 -0000 Message-ID: <4CA504AD.8000102@freebsd.org> Date: Thu, 30 Sep 2010 23:44:13 +0200 From: Andre Oppermann User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.9) Gecko/20100825 Thunderbird/3.1.3 MIME-Version: 1.0 To: Roman Divacky References: <4CA4BCD2.4070303@freebsd.org> <20100930172439.GA34369@freebsd.org> <4CA4CCF8.1050300@freebsd.org> <20100930174900.GA37733@freebsd.org> <20100930180417.GA39381@freebsd.org> In-Reply-To: <20100930180417.GA39381@freebsd.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-current@freebsd.org Subject: Re: Examining the VM splay tree effectiveness X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 30 Sep 2010 21:44:15 -0000 On 30.09.2010 20:04, Roman Divacky wrote: > On Thu, Sep 30, 2010 at 07:49:00PM +0200, Roman Divacky wrote: >> On Thu, Sep 30, 2010 at 07:46:32PM +0200, Andre Oppermann wrote: >>> On 30.09.2010 19:24, Roman Divacky wrote: >>>> are you aware of Summer of Code 2008 project by Mayur Shardul? >>> >>> I remember that there was this project but I never saw any numbers >>> or other outcome of it. Haven't checked p4 to look at the code >>> though. >> >> there's a little something: >> >> http://wiki.freebsd.org/MayurShardul/VM_Algorithm_Improvement > > and the actual patch + userspace implementation + benchmarking suite > is here: > > http://code.google.com/p/google-summer-of-code-2008-freebsd/downloads/detail?name=Mayur_Shardul.tar.gz&can=2&q= > > it looks like a solid work with solid results to me I just took a look (not in-depth though) at the patch and can't follow your conclusion. It is not ready to go into svn in its current state. Even though it is called a radix trie it doesn't look like one. On first impression it looks much more like an AA tree. A radix trie, which we already have in our network routing table code, is a variable length (mask) tree that does path compression. See net/radix.[ch] and http://en.wikipedia.org/wiki/Radix_tree Extrapolating in a complete guesstimating way from the lookup function I'd say it may perform only slightly better in an ideal case than a RB tree but with the added overall expense of requiring external memory to store the index and branch nodes. This is probably a nasty disadvantage. -- Andre