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_INVALID,DKIM_SIGNED, HTML_MESSAGE,MAILING_LIST_MULTI autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 14574 invoked from network); 13 Dec 2022 03:42:41 -0000 Received: from minnie.tuhs.org (50.116.15.146) by inbox.vuxu.org with ESMTPUTF8; 13 Dec 2022 03:42:41 -0000 Received: from minnie.tuhs.org (localhost [IPv6:::1]) by minnie.tuhs.org (Postfix) with ESMTP id 2DD9442384; Tue, 13 Dec 2022 13:42:19 +1000 (AEST) Received: from mail-ed1-f46.google.com (mail-ed1-f46.google.com [209.85.208.46]) by minnie.tuhs.org (Postfix) with ESMTPS id 92AA442383 for ; Tue, 13 Dec 2022 13:42:14 +1000 (AEST) Received: by mail-ed1-f46.google.com with SMTP id e13so15983311edj.7 for ; Mon, 12 Dec 2022 19:42:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bsdimp-com.20210112.gappssmtp.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=25291rjiZprPK1a3hddObgwewJv4HF2MSXpuvdP3wtY=; b=W1c3+3tR4Aoqh5PXg262bWNP2JEwA4kRJmLEJLN2QQyzcqBywZhKXxKf0y+HxOVxLb VpMQdB1JqpAVns/UlayYeNMwnnT4OYkPHc/tZIwhWB+ck60n5IgYYiFot5r+uca5fmoh +eF1YZShao7xAflPejXOaf3K5aSx1hjCSfsg6GZ/AAEeSAazaGiGqAbIf4C+FEyBSa6j ADZ7Kmm76JbLlBRVEq+9fh+N0DS1WsQCPscdtob/4gQ5JbjSMJsH2sUnRm3T3db6r/sj ssuf62gb31kO+7DUmHfmEOJsr1v60vbvqr1gQdWz8/VIe7Ly9/ecedf3AjI5XUnRNFwD n+AQ== 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=25291rjiZprPK1a3hddObgwewJv4HF2MSXpuvdP3wtY=; b=V61KREzw4nlRG31iw0x5V92ATlHWoOkl+rEthOUgZcXh1OojM0Q5M0VKo2yfWVENp7 13qMapBp/R1cRgLVNJKE82gx2QXZlxqd48SwEbF7Q+IsLy2M3mIi+j2xc2lVMo1h20lb CJqQxbn9HhkKDm8HF5SX4ggFTiXv9IZtFpSHt8wiojN76lAjljU0ACGmaBL/yBQ9vj5T ftWKfEMpWmZmMoh5xg3J+6HWl1nnbqQRmeeftXsJFzvTytp3/Jo+SczX8mWiZQH7T9k6 hP6W4BpA5GtwoPSkTq3zV8kAq4gDuAhWxeMbucYyrVwPTjPZSE9kvptcxtP78ynVMmNS 1kCQ== X-Gm-Message-State: ANoB5pkxlYCmpqJRnPDpt/XU8S2aL8lseHST629Jn6K6tl2duil5HwtY ZkC5O1Hf0xjbzUsRqKJq8F01jsPThakRO8vWoI3AmNKg2wXhYg== X-Google-Smtp-Source: AA0mqf56Qn31A1b/j8G1ykT7RGQRJpZAXNsuv/LWkvoVrd4CjvM9PG+04hvEZr7EY6FB5QyJ34Y8ZD8Ta0NUGodKJf8= X-Received: by 2002:a05:6402:1107:b0:463:9b53:cbf6 with SMTP id u7-20020a056402110700b004639b53cbf6mr79528954edv.173.1670902872883; Mon, 12 Dec 2022 19:41:12 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Warner Losh Date: Mon, 12 Dec 2022 20:41:01 -0700 Message-ID: To: Rudi Blom Content-Type: multipart/alternative; boundary="00000000000031544a05efad6476" Message-ID-Hash: OBAYJMKZ7P3Q6WWEWRC7M44K54KELWAN X-Message-ID-Hash: OBAYJMKZ7P3Q6WWEWRC7M44K54KELWAN X-MailFrom: wlosh@bsdimp.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 List-Id: The Unix Heritage Society mailing list Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: --00000000000031544a05efad6476 Content-Type: text/plain; charset="UTF-8" On Mon, Dec 12, 2022, 8:32 PM Rudi Blom wrote: > > I vaguely remember having read here about 'clever code' which took into > account the time a magnetic drum needed to rotate in order to optimise > access. > Yes. Many ways this was done. Biggest ones were interleaving and striding. Interleaving allowed one a little processing time for each sector while the disk fpu. So the next logical sector isn't the next physical... and the sectors are numbered in adjacent tracks to take into account rotation and seek times.... there is a lot of research here... Warner Similarly I can imagine that with resource restraints you sometimes need to > be clever in order to get your program to fit. Of course, any such > cleverness needs extra documentation. > > I only ever programmed in user space but even then without lots of comment > in my code I may already start wondering what I did after only a few months > past. > > Cheers, > uncle rubl > -- > The more I learn the better I understand I know nothing. > > --00000000000031544a05efad6476 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


On Mon, Dec 12, 2022, 8:32 PM Rudi Blom <rudi.j.blom@gmail.com> wrote:

I = vaguely remember having read here about 'clever code' which took in= to account the time a magnetic drum needed to rotate in order to optimise a= ccess.

Yes. Many ways this was done. Biggest ones were interleaving = and striding. Interleaving allowed one a little processing time for each se= ctor while the disk fpu. So the next logical sector isn't the next phys= ical... and the sectors are numbered in adjacent tracks to take into accoun= t rotation and seek times.... there is a lot of research here...

Warner

=
Similarly I can imagine that with resource res= traints you sometimes need to be clever in order to get your program to fit= . Of course, any such cleverness needs extra documentation.

<= /div>
I only ever programmed in user space but even then without=C2=A0l= ots of comment in my code I may already start wondering what I did after on= ly a few months past.

Cheers,
uncle rubl=
--
The more I= learn the better I understand I know nothing.

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