From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [PATCH] Stochastic Fair Blue queue discipline Date: Wed, 9 Apr 2008 19:49:54 +0200 Message-ID: <20080409174954.GD30885@one.firstfloor.org> References: <87skxxb8br.fsf@pirx.pps.jussieu.fr> <873apwrc4t.fsf@basil.nowhere.org> <7i3apwbblk.fsf@lanthane.pps.jussieu.fr> <20080408163252.GS16647@one.firstfloor.org> <7iwsn8s107.fsf@lanthane.pps.jussieu.fr> <20080408175353.GA17147@one.firstfloor.org> <7ik5j7ghgh.fsf@lanthane.pps.jussieu.fr> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Andi Kleen , netdev@vger.kernel.org To: Juliusz Chroboczek Return-path: Received: from one.firstfloor.org ([213.235.205.2]:51785 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752024AbYDIRpY (ORCPT ); Wed, 9 Apr 2008 13:45:24 -0400 Content-Disposition: inline In-Reply-To: <7ik5j7ghgh.fsf@lanthane.pps.jussieu.fr> Sender: netdev-owner@vger.kernel.org List-ID: > Random32 is initialised from get_random_bytes; so the per-cpu > pseudo-random sequences should be uncorrelated. I fail to see how an > arbitrary interleaving of uncorrelated good pseudo-random sequences > can fail to be good. They are not necessarily uncorreleated, especially on platforms which do have poor entropy support and when your initialization happens at boot time. Take a look at how the random pool starts in random.c. > > Looking at line 448 of sch_sfq.c in Linus' current HEAD, I see that > somebody else thinks the same as I do. So please let me know if sfq > needs fixed, or whether I can use net_random in sfb. A lot of people get this wrong, but this doesn't mean that the problem should be readded in new code again. -Andi