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,HTML_MESSAGE,MAILING_LIST_MULTI autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 30909 invoked from network); 8 Feb 2023 23:41:56 -0000 Received: from minnie.tuhs.org (50.116.15.146) by inbox.vuxu.org with ESMTPUTF8; 8 Feb 2023 23:41:56 -0000 Received: from minnie.tuhs.org (localhost [IPv6:::1]) by minnie.tuhs.org (Postfix) with ESMTP id 67E1040E4D; Thu, 9 Feb 2023 09:41:49 +1000 (AEST) Received: from mail-vk1-f172.google.com (mail-vk1-f172.google.com [209.85.221.172]) by minnie.tuhs.org (Postfix) with ESMTPS id 1280940D8C for ; Thu, 9 Feb 2023 09:41:45 +1000 (AEST) Received: by mail-vk1-f172.google.com with SMTP id b81so98099vkf.1 for ; Wed, 08 Feb 2023 15:41:45 -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=o2seEfmohFKZYyGNqnMCP7zApkv8gM7lnQQj8smYhoU=; b=OqwlJjTNVmRvap0GlAB4GsZ8ks0cSyvkMqN1j1fIdUJ0E0/feBLlhMxYLFm1D9qWfo 2sXuermw4L0WsmGsteH+xedJcQM5S7VuEz9WHkPZRGc0W8IfEhBwohhsrzXcdsPxbm4l HUdLmqx9mxwgdmYYcDlyDTTQO68q5+q7cCyX/Z2PjUJ8jtDCdMyLq/YPqGYsLjgAhSQM U8zj0nb9LyV4Zl1GsAy6g/cxvleqiko/O3tsJgitMPZCX4XoSavWTAFOVo7gY9sVxlk+ E8Zhkl41JiyoS6sUl6gGw4if7u1oDjxFb3QFa21k4jBxs62j/dtUTysui08v/dlZhoEd RckQ== 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=o2seEfmohFKZYyGNqnMCP7zApkv8gM7lnQQj8smYhoU=; b=ybHELMTE3Axm0Q0yPwsXFDf61Zo++aizef1v/XiT9gtPR9dhMi+AnMp3TgxVTTF8CM 6JYE9laXyyYr7/B9Ax/YjwqDn7yIrYt3jEB0/ZJu9+xy/M7361FT5ofhHG0sxZu24TxL gKNx4hFPvVaiAwqHcmAf7GHL3n8jqYwiQrb+lZ0FgUupE1TohKvnWt2Fwws4DMK3+Zc9 PxgovzRderBgjSp7IedFk25S/Qn55f9p5F/DG2lcALQeoC45d2K+UudYKD+X0870pPeL 3VbjIcCrrFb2qRSRmYinfN3KzO9eVvAUB+1ZSBaVtF6zuBDWjuxLM44U6wTnqYxpUAQM xIsQ== X-Gm-Message-State: AO0yUKWPdiWBHEiXhp59kczUT49XCE+xv5wKSMfO9sXlXHZ1LWNreXGP GKS3dCh9vwCchGC7t60wiVrZ0Wh/7s8jsQ5/Lc4= X-Google-Smtp-Source: AK7set/oADjfcB4NQW+dzoClVccFyERpZMg1+mSse7Xe/ww6fgOoPG0KwU7+PEOEDaC6rR1Qja1OteOuZVZuhDkbh6Y= X-Received: by 2002:a05:6122:1501:b0:3e6:da38:e22c with SMTP id d1-20020a056122150100b003e6da38e22cmr2249510vkq.29.1675899643891; Wed, 08 Feb 2023 15:40:43 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Rob Pike Date: Thu, 9 Feb 2023 10:40:32 +1100 Message-ID: To: Dan Cross Content-Type: multipart/alternative; boundary="000000000000f413fb05f438ca97" Message-ID-Hash: PFUJBOLBAHGYV6YU2SV6PZMQDVUTFESH X-Message-ID-Hash: PFUJBOLBAHGYV6YU2SV6PZMQDVUTFESH X-MailFrom: robpike@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: Doug McIlroy , TUHS X-Mailman-Version: 3.3.6b1 Precedence: list Subject: [TUHS] Re: Unix "Multiplexed Files" List-Id: The Unix Heritage Society mailing list Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: --000000000000f413fb05f438ca97 Content-Type: text/plain; charset="UTF-8" Not really an answer, but related. When I arrived at Bell Labs mid-1980, Greg Chesson was hard at work on mpx. When the Jerq/Blit work started up shortly after, we thought mpx would be the answer. I even wrote two different window systems using mpx as the controller, one of which was even itself called mpx, but the bugs in the kernel implementation were just too disruptive, and soon dmr's streams (not STREAMS - that was a shouty USG rename) proved the better, more robust mechanism. Other than some simple networking experiments, mpx(2) wasn't used much more as far as I know, and the Jerq effort demonstrated why. -rob On Thu, Feb 9, 2023 at 9:41 AM Dan Cross wrote: > The subject of Communication Files on DTSS came up recently, and Doug > linked to this wonderful note: > https://www.cs.dartmouth.edu/~doug/DTSS/commfiles.pdf > > Over on the Multicians list, I raised a question about the history of the > DTSS emulator on Multics in response to that, which sadly broke down into > antagonism, the details of which aren't terribly interesting. But Barry > Margolin suggested that the closest modern Unix analogue of Communication > Files were pseudo-TTYs, that had generated a dustup here. Doug's note > suggests that Plan 9's userspace filesystems, aided and abetted by mutable > namespaces and 9P as a common sharing mechanism, were a closer analogy. > > But I wonder if multiplexed files were perhaps an earlier analogue; my > cursory examination of mpx(2) shows some similarities to the description of > the DTSS mechanism. > > But I confess that I know very little about these, other than that they > seem to be an evolutionary dead end (they don't survive in any modern Unix > that I'm aware of, at any rate). I don't see much about them in my > archives; Paul Ruizendaal mentioned them tangentially in 2020 in relation > to non-blocking IO: they are, apparently, due to Chessen? > > Does anyone have the story here? > > - Dan C. > > --000000000000f413fb05f438ca97 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Not really an answer, but related.

When I arrived at Bell Labs m= id-1980, Greg Chesson was hard at work on mpx. When the Jerq/Blit work star= ted up shortly after, we thought mpx would be the answer. I even wrote two = different window systems using mpx as the controller, one of which was even= itself called mpx, but the bugs in the kernel implementation were just too= disruptive, and soon dmr's streams (not STREAMS - that was a shouty US= G rename) proved the better, more robust mechanism.

Other than some simple= networking experiments, mpx(2) wasn't used much more as far as I know,= and the Jerq effort demonstrated why.

-rob


On Thu, Feb 9, 2023 = at 9:41 AM Dan Cross <crossd@gmail.c= om> wrote:
The subject of Communication Files on DTSS came up recen= tly, and Doug linked to this wonderful note: https://www.cs.dartmo= uth.edu/~doug/DTSS/commfiles.pdf

Over on the Multici= ans list, I raised a question about the history of the DTSS emulator on Mul= tics in response to that, which sadly broke down into antagonism, the detai= ls of which aren't terribly interesting. But Barry Margolin suggested t= hat the closest modern Unix analogue of Communication Files were pseudo-TTY= s, that had generated a dustup here. Doug's note suggests that Plan 9&#= 39;s userspace filesystems, aided and abetted by mutable namespaces and 9P = as a common sharing mechanism, were a closer analogy.

<= div>But I wonder if multiplexed files were perhaps an earlier analogue; my = cursory examination of mpx(2) shows some similarities to the description of= the DTSS mechanism.

But I confess that I know ver= y little about these, other than that they seem to be an evolutionary dead = end (they don't survive in any modern Unix that I'm aware of, at an= y rate). I don't see much about them in my archives; Paul Ruizendaal me= ntioned them tangentially in 2020 in relation to non-blocking IO: they are,= apparently, due to Chessen?

Does anyone have the = story here?

=C2=A0 =C2=A0 =C2=A0 =C2=A0 - Dan C.

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