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 26156 invoked from network); 15 Dec 2022 14:20:29 -0000 Received: from minnie.tuhs.org (50.116.15.146) by inbox.vuxu.org with ESMTPUTF8; 15 Dec 2022 14:20:29 -0000 Received: from minnie.tuhs.org (localhost [IPv6:::1]) by minnie.tuhs.org (Postfix) with ESMTP id 66B0C42495; Fri, 16 Dec 2022 00:20:24 +1000 (AEST) Received: from mail-lf1-f43.google.com (mail-lf1-f43.google.com [209.85.167.43]) by minnie.tuhs.org (Postfix) with ESMTPS id 8A2034248C for ; Fri, 16 Dec 2022 00:20:20 +1000 (AEST) Received: by mail-lf1-f43.google.com with SMTP id b13so15892767lfo.3 for ; Thu, 15 Dec 2022 06:20:20 -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=RmrPnRJEWiPFYmAwLld4BkqWFN30HO8z5/lhV2Usyjk=; b=dzZFjhIRDzFjxv6mM8/18LEyRRiQnrxFQECd0whQEOuoRUOXcgNr98rwtKi3EX2oSi 7i+6Ya40MyeG6tKv8W8Pjch6VsZ5oRLSomelnjpSpr0NOiq1jVfBcNlKfUCMnymP9fE3 vUoV+rTnHPDj1MrFM+6sBiuHEx2q54GDeprBuwjjdofwozn/n2CMCMgAWYD7p7GthDo0 Ir/C+NP+9ti2k+b7PwQhg5FvzwsOztpQCq4Ln5v5nrtLiQvvv1gl+wu3quX8iE7NvEHr n36oKDJSxInb1TV5PmBwsw/kco+cQ3y0dDde7W4s7tE897Wq27MjvEJ5zFi1vMuRKtUo QlVg== 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=RmrPnRJEWiPFYmAwLld4BkqWFN30HO8z5/lhV2Usyjk=; b=aeCkP/UkyCKAtABCzaFJvdLFEkPO01+jwoQGgjbA+DY3hgjTwWVc/O9lZQWgMNn6uE vaAGa44XIRkHnahOlcar9QLUspo3v+/9a0MCsxKqORb31WBLW/dx3ybxhNbr26mUoh6d WYezXAYswJRpeVxt1jy8xyzheZmJPTyYhvOGeNfgY+2yjgHDuVbY5NTAquVHBF5cvdh8 D0ji74BcXmBrX7VuTpW1LkpIjGMEqw0Vb8bAT/KlRFw4pXVNOHwCcci8DFR9sbzZ/pqI xo5HuNcKMQcOL+d9uP+Q5HjWBn+5otZxnZNkotzcwtzBuD5n+BTOpG19e6d7mRmu4vxY Rwig== X-Gm-Message-State: AFqh2ko5qEdlRrFMg/FFCdyi/BCQ7hqeTbbDUQOZ/cBr+xDl7PmTG03M HI43CS6CuwKWgrjttuIkLmj7zD6p4qpigivID3k= X-Google-Smtp-Source: AMrXdXuHS1XUPvufRBOSKoB64hrErv1XxhvsAcveEcNVdEZRExQNiKtkgV//p2Wd83j+JoR7ePb9XejS/qHOZ2FWWXA= X-Received: by 2002:a05:6512:281a:b0:4b9:6159:f307 with SMTP id cf26-20020a056512281a00b004b96159f307mr502350lfb.86.1671113958578; Thu, 15 Dec 2022 06:19:18 -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> <20221215140659.GE21275@mcvoy.com> In-Reply-To: <20221215140659.GE21275@mcvoy.com> From: Dan Cross Date: Thu, 15 Dec 2022 09:18:42 -0500 Message-ID: To: Larry McVoy Content-Type: text/plain; charset="UTF-8" Message-ID-Hash: UST6UJSHE6NBE4I7RXPVQFSLW4CTPD37 X-Message-ID-Hash: UST6UJSHE6NBE4I7RXPVQFSLW4CTPD37 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: Bakul Shah , 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 9:07 AM Larry McVoy wrote: > On Thu, Dec 15, 2022 at 09:02:08AM -0500, Dan Cross wrote: > > 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. > > My mind went to similar thoughts. How did QNX manage the page cache? > Did they have mmap? I don't know if they did historically, but I kind of doubt it; QNX predates 4.2BSD, and I imagine there wasn't much influence from TENEX/PMAP). But they seem to now: https://www.qnx.com/developers/docs/7.1/#com.qnx.doc.neutrino.getting_started/topic/s1_resmgr_io_mmap.html No idea how they handle page caching. That's an interesting question, given how they adopted POSIX and try to at least give the outward appearance of being Unix-y. Given the emphasis on the message-based architecture, where messages can be sent between nodes, I doubt there's that much support for shared memory as a basis for IPC; I think they favored explicit messaging copying facilitated by the ukernel. Whether you could build something bespoke using the provided primitives is another matter. - Dan C.