From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=5.0 tests=MAILING_LIST_MULTI autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 27342 invoked from network); 19 Sep 2021 04:06:22 -0000 Received: from minnie.tuhs.org (45.79.103.53) by inbox.vuxu.org with ESMTPUTF8; 19 Sep 2021 04:06:22 -0000 Received: by minnie.tuhs.org (Postfix, from userid 112) id EC4119CAE2; Sun, 19 Sep 2021 14:06:15 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id 8AEE39CAB3; Sun, 19 Sep 2021 14:05:38 +1000 (AEST) Received: by minnie.tuhs.org (Postfix, from userid 112) id 9ADF79CAB3; Sun, 19 Sep 2021 14:05:34 +1000 (AEST) Received: from outgoing.mit.edu (outgoing-auth-1.mit.edu [18.9.28.11]) by minnie.tuhs.org (Postfix) with ESMTPS id 530B09CAB2 for ; Sun, 19 Sep 2021 14:05:33 +1000 (AEST) Received: from cwcc.thunk.org (pool-72-74-133-215.bstnma.fios.verizon.net [72.74.133.215]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 18J45PkG012139 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sun, 19 Sep 2021 00:05:26 -0400 Received: by cwcc.thunk.org (Postfix, from userid 15806) id 5BEE315C33EC; Sun, 19 Sep 2021 00:05:25 -0400 (EDT) Date: Sun, 19 Sep 2021 00:05:25 -0400 From: "Theodore Ts'o" To: Larry McVoy Message-ID: References: <202109161934.18GJYFsl881498@darkstar.fourwinds.com> <20210916194103.GK26820@mcvoy.com> <58BCBB10-A303-41C0-8620-992B107786BB@pobox.com> <202109171751.18HHpcAf3401326@darkstar.fourwinds.com> <20210917180710.GH18465@mcvoy.com> <20210917221149.GC3365@mcvoy.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210917221149.GC3365@mcvoy.com> Subject: Re: [TUHS] ATC/OSDI'21 joint keynote: It's Time for Operating Systems to Rediscover Hardware (Timothy Roscoe) X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: TUHS main list Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" On Fri, Sep 17, 2021 at 03:11:49PM -0700, Larry McVoy wrote: > > I'd suggest that is not Apple, but ARM. That was sort of the whole > > point of their BIG.little architecture with performance and efficiency > > cores. > > Credit to ARM, but M1 was where I saw it first. The M1 performance is > pretty impressive as well. Reminds me of LED bulbs: "Wait, these are > brighter, use less power, and cost less? How is that a thing?" ARM's BIG.little architecture dates back to 2011. Of course, they didn't *tell* anyone that they were doing this when before the chip was released, lest it get copied by their competitors. So they released a hacked-up version of the Linux kernel that supported their chip. And successive versions of BIG.little implemented by different ARM vendors had their own vendor-specific tweaks, with "board support kernels" that were heavily hacked up Linux kernels in code that was never sent upstream, since by the time vendors had released that chip, their kernel team was moved to working on a new project, where they would fork the current kernel version, and add completely different hacks for the next year's version of their System on a Chip (SOC). Proper support for differntly sized/powered cores didn't land in theb ppstream Linux until 2019, when Linux 5.0 finally acquired support for "Energy Aware Scheduling". So not only does hardware engineering take longer, but it's done in Sekrit, by software teams employed by chip manufacturers who often don't have any long-time attachment to the OS, and who will get reassigned to work the next year's SOC as soon as the current year's SOC is released. :-( Things have gotten a bit better in the last five years, but that's a pretty low bar, considering how horrible things were before that! - Ted