From owner-freebsd-arch@FreeBSD.ORG Wed Feb 25 10:23:32 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 1E3D5980 for ; Wed, 25 Feb 2015 10:23:32 +0000 (UTC) Received: from mailout.easymail.ca (mailout.easymail.ca [64.68.201.169]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id C5B7EE36 for ; Wed, 25 Feb 2015 10:23:31 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by mailout.easymail.ca (Postfix) with ESMTP id 20835E448 for ; Wed, 25 Feb 2015 05:23:30 -0500 (EST) X-Virus-Scanned: Debian amavisd-new at mailout.easymail.ca X-Spam-Flag: NO X-Spam-Score: -3.863 X-Spam-Level: X-Spam-Status: No, score=-3.863 required=5 tests=[ALL_TRUSTED=-1.8, AWL=-0.156, BAYES_00=-2.599, DNS_FROM_AHBL_RHSBL=0.692] Received: from mailout.easymail.ca ([127.0.0.1]) by localhost (easymail-mailout.easydns.vpn [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id byJcTmoHhP6E for ; Wed, 25 Feb 2015 05:23:30 -0500 (EST) Received: from bsddt1241.lv01.astrodoggroup.com (unknown [40.141.24.126]) (using TLSv1 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by mailout.easymail.ca (Postfix) with ESMTPSA id C6254E446 for ; Wed, 25 Feb 2015 05:23:29 -0500 (EST) Message-ID: <54EDA2A6.9080209@astrodoggroup.com> Date: Wed, 25 Feb 2015 02:23:34 -0800 From: Harrison Grundy User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: freebsd-arch@freebsd.org Subject: Re: locks and kernel randomness... References: <20150224231921.GQ46794@funkthat.com> <1424822522.1328.11.camel@freebsd.org> <20150225002956.GT46794@funkthat.com> <2F49527F-2F58-4BD2-B8BE-1B1190CCD4D0@bsdimp.com> <54ED5656.50607@astrodoggroup.com> <20150225090638.GB74514@kib.kiev.ua> <54ED92E5.4010803@astrodoggroup.com> <54ED9A4B.4060802@astrodoggroup.com> <20150225100512.GC74514@kib.kiev.ua> <54EDA128.4000107@astrodoggroup.com> <20150225102113.GD74514@kib.kiev.ua> In-Reply-To: <20150225102113.GD74514@kib.kiev.ua> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit 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: Wed, 25 Feb 2015 10:23:32 -0000 On 02/25/15 02:21, Konstantin Belousov wrote: > On Wed, Feb 25, 2015 at 02:17:12AM -0800, Harrison Grundy wrote: >> >> >> On 02/25/15 02:05, Konstantin Belousov wrote: >>> On Wed, Feb 25, 2015 at 01:47:55AM -0800, Harrison Grundy >>> wrote: >>>> Three choices here are attached here: >>>> >>>> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=197922 >>>> >>>> The only remaining one I don't have a patch for is putting a >>>> "real" PRNG in ULE. >>>> >>>> At this point, as far as ULE goes, It just comes down to >>>> picking from one of those approaches. >>> >>> The third patch, ' Creates sched_random, using the system used >>> in cpu_search.', seems to miss updating the dpcpu randomval in >>> sched_random(), isn't it ? >>> >> >> It does exactly what cpu_search does. > I do not see how it does exactly what cpu_search does. > > cpu_search is updating *rndptr: rnd = (*rndptr = *rndptr * 69069 + > 5) >> 26; > > while code in patch is: + rndptr = DPCPU_PTR(randomval); + > rnd = (*rndptr * 69069 + 5) >> 26; > > where is the write to *rndptr ? My mistake. I'll update the patch accordingly. Interestingly enough, ULE doesn't seem to care about losing randomness there either. --- Harrison