From owner-freebsd-arch@FreeBSD.ORG Tue Feb 24 19:44:37 2015 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 16B39876; Tue, 24 Feb 2015 19:44:37 +0000 (UTC) Received: from gold.funkthat.com (gate2.funkthat.com [208.87.223.18]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "gold.funkthat.com", Issuer "gold.funkthat.com" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id DD78BCCC; Tue, 24 Feb 2015 19:44:36 +0000 (UTC) Received: from gold.funkthat.com (localhost [127.0.0.1]) by gold.funkthat.com (8.14.5/8.14.5) with ESMTP id t1OJiWV4005178 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 24 Feb 2015 11:44:32 -0800 (PST) (envelope-from jmg@gold.funkthat.com) Received: (from jmg@localhost) by gold.funkthat.com (8.14.5/8.14.5/Submit) id t1OJiVUe005177; Tue, 24 Feb 2015 11:44:31 -0800 (PST) (envelope-from jmg) Date: Tue, 24 Feb 2015 11:44:31 -0800 From: John-Mark Gurney To: Ian Lepore Subject: Re: locks and kernel randomness... Message-ID: <20150224194431.GM46794@funkthat.com> References: <20150224012026.GY46794@funkthat.com> <20150224015721.GT74514@kib.kiev.ua> <54EBDC1C.3060007@astrodoggroup.com> <20150224024250.GV74514@kib.kiev.ua> <20150224174053.GG46794@funkthat.com> <1E4A5E62-6E06-48BA-B5C5-9BD05811CDEF@bsdimp.com> <20150224183051.GJ46794@funkthat.com> <1424804722.3293.12.camel@freebsd.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1424804722.3293.12.camel@freebsd.org> X-Operating-System: FreeBSD 9.1-PRERELEASE amd64 X-PGP-Fingerprint: 54BA 873B 6515 3F10 9E88 9322 9CB1 8F74 6D3F A396 X-Files: The truth is out there X-URL: http://resnet.uoregon.edu/~gurney_j/ X-Resume: http://resnet.uoregon.edu/~gurney_j/resume.html X-TipJar: bitcoin:13Qmb6AeTgQecazTWph4XasEsP7nGRbAPE X-to-the-FBI-CIA-and-NSA: HI! HOW YA DOIN? can i haz chizburger? User-Agent: Mutt/1.5.21 (2010-09-15) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (gold.funkthat.com [127.0.0.1]); Tue, 24 Feb 2015 11:44:32 -0800 (PST) Cc: Konstantin Belousov , Harrison Grundy , freebsd-arch@freebsd.org X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 24 Feb 2015 19:44:37 -0000 Ian Lepore wrote this message on Tue, Feb 24, 2015 at 12:05 -0700: > On Tue, 2015-02-24 at 10:30 -0800, John-Mark Gurney wrote: > > Warner Losh wrote this message on Tue, Feb 24, 2015 at 11:03 -0700: > > > > > > > On Feb 24, 2015, at 10:40 AM, John-Mark Gurney wrote: > > > > > > > > Warner Losh wrote this message on Tue, Feb 24, 2015 at 07:56 -0700: > > > >> Then again, if you want to change random(), provide a weak_random() that???s > > > >> the traditional non-crypto thing that???s fast and lockless. That would make it easy > > > >> to audit in our tree. The scheduler doesn???t need cryptographic randomness, it > > > >> just needs to make different choices sometimes to ensure its notion of fairness. > > > > > > > > I do not support having a weak_random... If the consumer is sure > > > > enough that you don't need a secure random, then they can pick an LCG > > > > and implement it themselves and deal (or not) w/ the locking issues... > > > > > > > > It appears that the scheduler had an LCG but for some reason the authors > > > > didn't feel like using it here.. > > > > > > Why don???t you support having a common random routine that???s to mix the > > > pot, but not cryptographically secure? Lots of algorithms use them, and having > > > a common one would keep us from reinventing the wheel. > > > > Why can't these algorithms use a cryptographically secure RNG instead? > > No one has truely answered that point.. Everyone says they want to use > > an insecure RNG, but the real question is, why can't/shouldn't these > > algorithms use a CSPRNG? > > Because of performance. Not everything needs crypto-strength > randomness. LOL... If you need something that gives you more than 500MB/sec of randomness, using an LCG is the least of your worries, and you need to be implementing you're own anyways... > The problem here is that you are never going to accept the validity of > that statement no matter how many of us complain over and over again > about this kind of thing. You've got some religion that the rest of us Give me examples of code in the tree that needs high performance, low quality randomness, and I will agree with you and provide the interface, but as long as you continue to create strawmen, I won't... The example we've been discussing of the scheduler is called LESS than once a second! OMG! soo many cycles wasted! > don't buy into, and you've got it fervently enough that you'll just keep > saying the same mindless things over and over again until we all get > bored and wander away. Just like you keep mindless saying that people need an LCG because performance, trust us! Performance! Performance! > And freebsd gets a little more bloated and a little slower and a lot > less able to run on anything except the very fastest hardware that was > just released last week. Thanks for "improving" it in that way. Again, give me an example of calling random(9) more than 100 times per second, or testing w/ my patch, and showing more than .01% cpu in random and I'll have an honest discussion about this... But you're speculating on performance issues w/o numbers... -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."