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=-1.2 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,NICE_REPLY_A,RCVD_IN_DNSWL_NONE autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 4966 invoked from network); 17 Aug 2020 22:06:03 -0000 Received: from minnie.tuhs.org (45.79.103.53) by inbox.vuxu.org with ESMTPUTF8; 17 Aug 2020 22:06:03 -0000 Received: by minnie.tuhs.org (Postfix, from userid 112) id 97F3C9E1BB; Tue, 18 Aug 2020 08:05:59 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id 9C74C9CAB6; Tue, 18 Aug 2020 08:05:19 +1000 (AEST) Authentication-Results: minnie.tuhs.org; dkim=pass (1024-bit key; unprotected) header.d=kilonet.net header.i=@kilonet.net header.b="T+zOpg/1"; dkim-atps=neutral Received: by minnie.tuhs.org (Postfix, from userid 112) id F00DB9C8BB; Tue, 18 Aug 2020 08:05:15 +1000 (AEST) Received: from p3plsmtpa09-02.prod.phx3.secureserver.net (p3plsmtpa09-02.prod.phx3.secureserver.net [173.201.193.231]) by minnie.tuhs.org (Postfix) with ESMTPS id AC9E99C8BB for ; Tue, 18 Aug 2020 08:05:14 +1000 (AEST) Received: from medusa.kilonet.net ([108.30.24.253]) by :SMTPAUTH: with ESMTPA id 7nFgkopYhhpWr7nFhkGAzQ; Mon, 17 Aug 2020 15:05:13 -0700 X-CMAE-Analysis: v=2.3 cv=cLGeTWWN c=1 sm=1 tr=0 a=DPaANz7MSPdDiKJlpBZCUg==:117 a=DPaANz7MSPdDiKJlpBZCUg==:17 a=IkcTkHD0fZMA:10 a=y4yBn9ojGxQA:10 a=xbr3S9fc9ZTQigv5b1QA:9 a=QEXdDO2ut3YA:10 X-SECURESERVER-ACCT: krewat@kilonet.net Received: from [199.89.231.101] (ender.kilonet.net [199.89.231.101]) by medusa.kilonet.net (8.14.8/8.15.1) with ESMTP id 07HM5C5Y029558 for ; Mon, 17 Aug 2020 18:05:12 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kilonet.net; s=default; t=1597701912; bh=C+PLe6hqhHl5fe8XrNwIXk9YE+x0UMXgnfVKWHB2cG4=; h=Subject:To:References:From:Date:In-Reply-To; b=T+zOpg/1NDgvJ3mmp50z+GzSccmkk9lllBtZTODbJ0iCoEGRvk2AYWRAOJbVPNIr/ gl/QnZYHgoTiBTiP+I8Vh2Ivya7p+0icQvR5jicuL+m28RPvxPBPGc6LFmkzMnwCFM eZ5koJK5udWI8gK77Cq5gxU0u2Ycsyrb+BCBmL+s= To: tuhs@minnie.tuhs.org References: <20200817192715.22D9518C09E@mercury.lcs.mit.edu> <20200817193050.GC11413@mcvoy.com> From: Arthur Krewat Message-ID: <88b97e2f-ddd2-8c5b-f2ac-3d4305c6ae86@kilonet.net> Date: Mon, 17 Aug 2020 18:05:09 -0400 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-CMAE-Envelope: MS4wfN76bN78rG1Cnhvphi7QWYoSXHiTX84eOrjgQP9cRh2R0OORea6rKTud0o8bXpLDiyYtKj8Ms/H7i4o7uw+dZeCY4c6TWMlEU/usGPmcHIjBEv/b3JzY T5IPiywX9q+6LudMlGm4b2SI+cxiuzUh/glwcHIx99juSlTlQ80EcewH5vjW92lNplrVDGy8uOJC5w== Subject: Re: [TUHS] Memory management in Dennis Ritchie's C Compiler 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: , Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" On 8/17/2020 3:50 PM, Paul Winalski wrote: > VAX/VMS had the equivalent of mmap(2) back in 1978. You can specify a > range of contiguous pages in virtual memory and associate that with a > (page-aligned) range of blocks in a file. The blocks in the file act > as backing store for the virtual memory. I, and my boss, took advantage of that while converting his database software from TOPS-10 to VMS. His TOPS-10 implementation used various ways to optimize I/O from/to disk. On VMS, our benchmarks showed that as long as we understood the paging size, performance was about the same. RP06 vs. I think something bigger. Maybe RP07. But even still, it proved the operating system virtual memory system was up to the task. I seem to remember there was a way to sync a page after you wrote it just to make sure it was committed to disk. It worked so well that I also seem to recall that we used some of that file space as heap. art k.