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 6000 invoked from network); 15 Dec 2022 02:55:05 -0000 Received: from minnie.tuhs.org (50.116.15.146) by inbox.vuxu.org with ESMTPUTF8; 15 Dec 2022 02:55:05 -0000 Received: from minnie.tuhs.org (localhost [IPv6:::1]) by minnie.tuhs.org (Postfix) with ESMTP id 368E74239F; Thu, 15 Dec 2022 12:54:59 +1000 (AEST) Received: from mcvoy.com (mcvoy.com [192.169.23.250]) by minnie.tuhs.org (Postfix) with ESMTPS id 3D4404239E for ; Thu, 15 Dec 2022 12:54:54 +1000 (AEST) Received: by mcvoy.com (Postfix, from userid 3546) id C6E6135E926; Wed, 14 Dec 2022 18:54:53 -0800 (PST) Date: Wed, 14 Dec 2022 18:54:53 -0800 From: Larry McVoy To: Bakul Shah Message-ID: <20221215025453.GY20511@mcvoy.com> References: <20221211200327.GC8801@mcvoy.com> <8F5B431B-3789-42C7-8E34-0B6A417B41CF@iitbombay.org> <4A770CCE-2BC9-4DA7-B3D7-71AF9A23F79E@iitbombay.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4A770CCE-2BC9-4DA7-B3D7-71AF9A23F79E@iitbombay.org> User-Agent: Mutt/1.5.24 (2015-08-30) Message-ID-Hash: OD76O2C52CIDXV25ZLCQ3WBPCMOYXGAB X-Message-ID-Hash: OD76O2C52CIDXV25ZLCQ3WBPCMOYXGAB X-MailFrom: lm@mcvoy.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-tuhs.tuhs.org-0; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: The Eunuchs Hysterical Society X-Mailman-Version: 3.3.6b1 Precedence: list Subject: [TUHS] Re: Clever code (was Re: Re: Stdin Redirect in Cu History/Alternatives? List-Id: The Unix Heritage Society mailing list Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: Wasn't there some statement that QNX dropped some of these? Copy plus context switch? On Wed, Dec 14, 2022 at 04:29:45PM -0800, Bakul Shah wrote: > On Dec 11, 2022, at 7:09 PM, Andrew Warkentin wrote: > > > > It's not necessarily true that microkernels are significantly slower. > > uKernels are usually quite fast as they do so little. What can be slow > is emulating a Unix like OS on top due to context switches. For instance, > a user process doing read() will have the following context switches: > > userProc->uK->FileSystem->uK->diskDriver->uk->FileSysem->uK->userProc > > or worse (I didn't account for a few things). Because of this even some > uKernels run a few critical services + drivers in the supervisor mode. > But overall slowdown of such a unix emulation will very much depend on the > workload and also what kind of performance improvements you are willing to > try in a complex kernel vs same services running in user mode. > > At present the linux kernel has about 31+ Million lines (accounting for > all architectures, filesystems, device drivers etc.). The FreeBSD 13.x > kernel is about 8.7M LoC (of which 44-45% are in device drivers). I only > counted .c and .h files. In contract FreeBSD 2.2.2 kernel has ~554K LoC. > This LoC growth is entirely understandable but I wonder how things may > have turned out in an alternate universe of uKernel based designs.... -- --- Larry McVoy Retired to fishing http://www.mcvoy.com/lm/boat