From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by finch.gentoo.org (Postfix) with ESMTPS id 35FE31396D9 for ; Mon, 13 Nov 2017 04:29:11 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 1C0D3E0EFA; Mon, 13 Nov 2017 04:29:02 +0000 (UTC) Received: from resqmta-ch2-11v.sys.comcast.net (resqmta-ch2-11v.sys.comcast.net [IPv6:2001:558:fe21:29:69:252:207:43]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id C5354E0EA9 for ; Mon, 13 Nov 2017 04:29:00 +0000 (UTC) Received: from resomta-ch2-19v.sys.comcast.net ([69.252.207.115]) by resqmta-ch2-11v.sys.comcast.net with ESMTP id E6Mle7RjSWXhtE6Mlec26g; Mon, 13 Nov 2017 04:28:59 +0000 Received: from [192.168.1.13] ([73.173.137.35]) by resomta-ch2-19v.sys.comcast.net with SMTP id E6MkeIb875Ls1E6MleZaq6; Mon, 13 Nov 2017 04:28:59 +0000 Subject: Re: [gentoo-dev] Manifest2 hashes, take n+1-th: 3 hashes for the tie-breaker case To: gentoo-dev@lists.gentoo.org References: <1508440120.19870.14.camel@gentoo.org> <26AE424C-19DF-4059-A7DE-8ED6D605FF2C@gentoo.org> <1508817879.1688.6.camel@gentoo.org> <1508818272.1688.7.camel@gentoo.org> <88fa2503-11de-2f34-b4a9-58159f14a1ac@gentoo.org> From: Joshua Kinard Message-ID: <1ba24f4a-393f-677e-58e6-539e7a3bf23d@gentoo.org> Date: Sun, 12 Nov 2017 23:28:56 -0500 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-dev@lists.gentoo.org Reply-to: gentoo-dev@lists.gentoo.org MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-CMAE-Envelope: MS4wfHX7KqGXv34saUEZIK3UXLVbGRlO8se26kw24CJypRCkyB4iVc6QOPrFeHDMEM+szXLm4iNnVKYILF3OSgndTiIH/iIh8cF7oII967nweUgemTphgNuP AurCeBKmjX4dJ7gQPfKNg6ZhB+FHOucvKiIyxuptDvVDAZ+OU4xcPfBH0zOSHQgXE/bRA4apkKkT/g== X-Archives-Salt: af855e8f-4ef6-4248-850a-907042993601 X-Archives-Hash: d2375aeca2d54d1626d1f10e40fa8ee3 On 11/12/2017 22:48, Gordon Pettey wrote: > On Sun, Nov 12, 2017 at 8:22 PM, Joshua Kinard wrote: > >> Minor clarification, old single core //and// uni-processor. Some older >> machines have multiple physical CPUs that are single-core. Threading >> should be >> okay on these, as long as the thread count stays under NR_CPUS. >> >> I also have a really old single-CPU system, MIPS (obviously). Not the >> fastest >> on the block compared to the other equipment I've got, but does anyone >> know of >> any simple timing scripts/programs available that can benchmark some of >> these >> proposed digest hashes? If they turn out to be reasonably quick on my old >> machine, I doubt then that speed will be too much of an issue. >> > > Even on your "old single-CPU MIPS" system, what percentage of time is > spent verifying manifest hashes compared to actually building/installing? > The whole "slow and/or multiple hashes will cause problems" argument > seems specious. It appears that you have misread my inquiry quite severely. I am not terribly interested in the whole argument of "multiple hashes" or "slow hashes". It's just my curiosity wanting to know if there's a reliable way to benchmark, on the command line, several common/known digest hashing algorithms. For my MIPS systems, the type of CPU and system architecture is very different between each machine. Being able to compare between each of them might have uses down the road. But also having a rough idea of how the actual hashes perform might also be of use to the discussion. Only to enlighten, not to push a particular side. -- Joshua Kinard Gentoo/MIPS kumba@gentoo.org 6144R/F5C6C943 2015-04-27 177C 1972 1FB8 F254 BAD0 3E72 5C63 F4E3 F5C6 C943 "The past tempts us, the present confuses us, the future frightens us. And our lives slip away, moment by moment, lost in that vast, terrible in-between." --Emperor Turhan, Centauri Republic