From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael K. Edwards" Subject: Re: Extensible hashing and RCU Date: Thu, 22 Feb 2007 18:31:29 -0800 Message-ID: References: <20070222234900.27633.qmail@science.horizon.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: johnpol@2ka.mipt.ru, akepner@sgi.com, bcrl@kvack.org, dada1@cosmosbay.com, davem@davemloft.net, netdev@vger.kernel.org To: "linux@horizon.com" Return-path: Received: from wr-out-0506.google.com ([64.233.184.226]:5895 "EHLO wr-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750755AbXBWCbd (ORCPT ); Thu, 22 Feb 2007 21:31:33 -0500 Received: by wr-out-0506.google.com with SMTP id i21so356538wra for ; Thu, 22 Feb 2007 18:31:32 -0800 (PST) In-Reply-To: <20070222234900.27633.qmail@science.horizon.com> Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 22 Feb 2007 18:49:00 -0500, linux@horizon.com wrote: > The rehash-every-10-minutes detail is theoretically unnecessary, > but does cover the case where a would-be attacker *does* get a chance > to look at a machine, such as by using routing delays to measure the > effectiveness of a collision attempt. AOL -- and that's one of the reasons why RCUing hashes is a nightmare in practice, if you care about smooth peristalsis. Again, the resizing headache is just the canary in the coal mine. > If you want to test your distribution for randomness, go have a look > at Knuth volume 2 (seminumerical algorithms) and see the discussion of > the Kolmogorov-Smirnov test. Some lumpiness is *expected* in a truly > random distribution. Ah, Kolmogorov-Smirnov, the astronomer's friend. Somewhere on a DAT in my garage lies a rather nice implementation of K-S tests on censored data for the Mirella/Mirage Forth image analysis package. If you want something industrial-strength, easy to use, and pretty besides, I recommend SM (http://www.astro.princeton.edu/~rhl/sm/), which will cost you $500 U.S. for a department-scale license. SM so utterly exceeds the capabilities of gnuplot it isn't even funny. But then, while you don't always get what you pay for, you rarely fail to pay for what you get, sooner or later, in one currency or another. Cheers, - Michael