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 18250 invoked from network); 9 Mar 2023 08:21:44 -0000 Received: from minnie.tuhs.org (50.116.15.146) by inbox.vuxu.org with ESMTPUTF8; 9 Mar 2023 08:21:44 -0000 Received: from minnie.tuhs.org (localhost [IPv6:::1]) by minnie.tuhs.org (Postfix) with ESMTP id D1AB9412D5; Thu, 9 Mar 2023 18:21:38 +1000 (AEST) Received: from mail-wm1-x333.google.com (mail-wm1-x333.google.com [IPv6:2a00:1450:4864:20::333]) by minnie.tuhs.org (Postfix) with ESMTPS id DB46A41293 for ; Thu, 9 Mar 2023 18:21:32 +1000 (AEST) Received: by mail-wm1-x333.google.com with SMTP id j19-20020a05600c1c1300b003e9b564fae9so2968976wms.2 for ; Thu, 09 Mar 2023 00:21:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1678350090; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=eUvsuAPJCRkny2Ml32yFcpLDWmcMe0rz7gIcLHBPAGk=; b=pI57hw5YaLvHNTMuVMyrgsIy7cZbbzr5V89dRMReC1tGn1KP1D/1Py2IxoxkP6EPw/ yJ9aZODO1z2UmdbiwgNWbSE6IRyxFmwahVptUdNrm8ze40iDk+kQ2iwQY65Scqoo4Rhz yo0c93Y7hB9C7LXYF+BUpGZ4fRhGvV/sjmoqv1UBBjyGHEbSCY0yg58JmEz1nHKyjF15 NEV61fj48IuUY+9pqmADS+hwsO8ohoituczhZZq8Bml068Tm/fZDVQJzUPxZT82xkGlE D802l/OgcMpfK9I69lPflyA5Icc7xE2s1puJHCiTURzcREmXBm9bRsSwEzOeGLcu9XIn Oh4A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1678350090; 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=eUvsuAPJCRkny2Ml32yFcpLDWmcMe0rz7gIcLHBPAGk=; b=hmxTNWYGbXMd6nUy+9E89gc5qaeOYGVy4lxyErczn9zF+x4cWdv6G7mDilQLAKhL72 CJxmmhbLug8Fr1c2y5xJ8P6bEPeNnfFgFc0YI4LpdZ9wVPDnFJRQHwxLDTjFbfjH4Dzl OuSJH4w1dn/3GytrdoMj98tOkIMjPkbtPZC3pGSxhMxFbMx8N1zrbIbw0R/5re5Bm1v+ zlF7GLcyCYUw4Yb3eBKJmMIgFT38jTs2l0Byw2l/m5hJyq/QRISzpDtiNiFdKTvPx0tR YpDTHtFjtnk6qwGxZG+xL9YPCWDqGSfxBB8LKWCZonDlGHq9V8PtJQIM95XitR1+E+i/ qeyQ== X-Gm-Message-State: AO0yUKXN2FGjAcVS0mYzo3AT+Wy5rTLqWgbXp2gXwAgqegXBEOTjrlkC JkjAQHYDiS/oW/lYuv/JAhhSvpqpZDJT7nNf2fIIfqDi X-Google-Smtp-Source: AK7set9J1QW6eHpegqo2E7CIWLNHAgm2N4X1P2+4xlPCiETlNv57zm6kw7BrONrHMAJixF+G/yC/RhWpbjl+PUWWU6A= X-Received: by 2002:a05:600c:1:b0:3eb:5824:f0ec with SMTP id g1-20020a05600c000100b003eb5824f0ecmr4889103wmc.2.1678350090365; Thu, 09 Mar 2023 00:21:30 -0800 (PST) MIME-Version: 1.0 References: <20230308131008.0C2D018C07B@mercury.lcs.mit.edu> In-Reply-To: <20230308131008.0C2D018C07B@mercury.lcs.mit.edu> From: Kenneth Goodwin Date: Thu, 9 Mar 2023 03:21:19 -0500 Message-ID: To: Noel Chiappa Content-Type: multipart/alternative; boundary="000000000000f1f0a405f67354a8" Message-ID-Hash: MQCBR3K7NVLVOC525RCAQCPMW7ERRUQF X-Message-ID-Hash: MQCBR3K7NVLVOC525RCAQCPMW7ERRUQF X-MailFrom: kennethgoodwin56@gmail.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; 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: 'Huge' file support removed from PWB1 List-Id: The Unix Heritage Society mailing list Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: --000000000000f1f0a405f67354a8 Content-Type: text/plain; charset="UTF-8" I have not seen the UNIX kernel source code in quite a while, but as I recall the double indirect block algorithm did not kick in until the file exceeded a certain threshold. So it would not make sense to remove the code for performance reasons. Perhaps this is more likely due to the use of larger logical block sizes.... Is the code physically removed or IFDEF'd out for conditional compilation? Perhaps someone decided that programmers would never need to test code on large files.. On Wed, Mar 8, 2023, 8:10 AM Noel Chiappa wrote: > In PWB1, support for 'huge' files appears to have been removed. If one > compares bmap() in PWB1'S subr.c with V6's, the "'huge' fetch of double > indirect block" code is gone. I guess PWB didn't need very large (> > 8*256*512 > = 1,048,576 bytes) files? I'm not sure what the _benefits_ of removing it > were, though - unless PWB was generating lots of files of between 7*256*512 > and 8*256*512 bytes in length, and they wanted to avoid the overhead of the > double-indirect block? (The savings in code space are derisory - unlike in > LSX/MINI-UNIX.) Anyone know? > > Noel > --000000000000f1f0a405f67354a8 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
I have not seen the UNIX kernel source code in quite a wh= ile, but as I recall the double indirect block algorithm did not kick in un= til the file exceeded a certain threshold. So it would not make sense to re= move the code for performance reasons.

Perhaps this is more likely due to the use of larger logical bloc= k sizes....

Is the code = physically removed or IFDEF'd out for conditional compilation?

Perhaps someone decided that pro= grammers would never need to test code on large files..

On Wed, Mar 8,= 2023, 8:10 AM Noel Chiappa <= jnc@mercury.lcs.mit.edu> wrote:
In PWB1, support for 'huge' files appears to have been removed.= If one
compares bmap() in PWB1'S subr.c with V6's, the "'huge'= ; fetch of double
indirect block" code is gone. I guess PWB didn't need very large (= > 8*256*512
=3D 1,048,576 bytes) files? I'm not sure what the _benefits_ of removin= g it
were, though - unless PWB was generating lots of files of between 7*256*512=
and 8*256*512 bytes in length, and they wanted to avoid the overhead of the=
double-indirect block? (The savings in code space are derisory - unlike in<= br> LSX/MINI-UNIX.) Anyone know?

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 Noel
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