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=-0.8 required=5.0 tests=DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FROM,MAILING_LIST_MULTI autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 24053 invoked from network); 15 Dec 2022 14:03:56 -0000 Received: from minnie.tuhs.org (50.116.15.146) by inbox.vuxu.org with ESMTPUTF8; 15 Dec 2022 14:03:56 -0000 Received: from minnie.tuhs.org (localhost [IPv6:::1]) by minnie.tuhs.org (Postfix) with ESMTP id 34B1242489; Fri, 16 Dec 2022 00:03:52 +1000 (AEST) Received: from mail-lf1-f54.google.com (mail-lf1-f54.google.com [209.85.167.54]) by minnie.tuhs.org (Postfix) with ESMTPS id E3AC342478 for ; Fri, 16 Dec 2022 00:03:46 +1000 (AEST) Received: by mail-lf1-f54.google.com with SMTP id q6so15773447lfm.10 for ; Thu, 15 Dec 2022 06:03:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=BSfwqVDsSDJc0/virqxICI2PmBSUpZsS0irikcz/xnU=; b=Fic3LHGmRCt9us5XZFP1I9LkdEm5+ZmLag/mgHz4dQSDdaDymRzR45RcL8I0LuYdgQ cKE7bRhjlVJLPeGX80Ssn/7uIF7og342+XhBN271oD7yGDWTBOr/cdLsPMCmBlWCocUH tv2SDnKbrCQoUnQy3vGNv6grXPPwQZuCqT7Sc+GkcQ/gePFxr/VeHYiexwckZQAwS+HF nwYgBg0DQB+zXgCVgmk8XsjfwKBnDVyHxCDc2lcb2cSww0H3+2D8XZZ1Q+/4ua7idRZ2 mdofdsfKU+2Aa9hAIc8g9XeLpEXQzRsfQluVQ42fq5w8w5xH8lAj6asAHWubnvZEb3A2 wmLw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=BSfwqVDsSDJc0/virqxICI2PmBSUpZsS0irikcz/xnU=; b=IVU9fjTNayRB0KB3UscEOWGcZ/8OE5bv7H9XTnJheJOVBqiydXPbAXyt18vq8QHIJi yAvUOzRKmowhW5NbbzY5WaLvUX5KFC7+u37It11bbNsGRBcaQE7EQa3h/d4qvqfjokE9 q+mNE2LqywBHyGjmPoaiPWxttH5PfKPAz0brmDXsOZiP+vyEA/D4l4wHeLWWUdM/RZt7 SFP56ljtByHyVrp3tIfQewbg6jw9hapKHHZPlnMy4vMaXarmBNW6KrH2RlHUNyRIJc1x NytnUEZ1/WWICp7esKcXGTUBf1B9rH/TXMxW5JZi/575f0Bov6kpMiRLoUaBLWKguBhL x1Pg== X-Gm-Message-State: ANoB5pmiypaz9iYmkpjdw5+43fueRv5LTMIrYtZ5uFld+76KxhyYVzIJ g7C+r5XMemFAmeZQBvZOrGFa7ydsem2ngB1Wplw= X-Google-Smtp-Source: AA0mqf6wn5bDSDeAYA6HLf1guNY+zcsoYJZFthl4QmYU1v6CepDl19wOIYihCBuzKh9FFpR6LTBH9R/am8f5o7CnV1g= X-Received: by 2002:a05:6512:31d1:b0:4ae:6bbc:e8af with SMTP id j17-20020a05651231d100b004ae6bbce8afmr27722168lfe.411.1671112964834; Thu, 15 Dec 2022 06:02:44 -0800 (PST) MIME-Version: 1.0 References: <20221211200327.GC8801@mcvoy.com> <8F5B431B-3789-42C7-8E34-0B6A417B41CF@iitbombay.org> <4A770CCE-2BC9-4DA7-B3D7-71AF9A23F79E@iitbombay.org> <20221215025453.GY20511@mcvoy.com> In-Reply-To: From: Dan Cross Date: Thu, 15 Dec 2022 09:02:08 -0500 Message-ID: To: Bakul Shah Content-Type: text/plain; charset="UTF-8" Message-ID-Hash: GCJY4XQCCGKQIUK6YOB7IZSCPKFOJDBE X-Message-ID-Hash: GCJY4XQCCGKQIUK6YOB7IZSCPKFOJDBE X-MailFrom: crossd@gmail.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: On Thu, Dec 15, 2022 at 12:38 AM Bakul Shah wrote: > Don't see how unless they put multiple related services in the same > address space, which reduces context switching but tends toward a > monokernel (& increased coupling). Unless I am misunderstanding you. I don't see why two services in a microkernel couldn't arrange to share a region of memory and implement bidirectional queues between themselves. With an appropriate signalling mechanism, you'd still be context switching but avoiding a lot of copying. - Dan C. > > On Dec 14, 2022, at 6:54 PM, Larry McVoy wrote: > > > > 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 >