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=-1.0 required=5.0 tests=MAILING_LIST_MULTI, UNPARSEABLE_RELAY autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 16359 invoked from network); 9 Mar 2023 12:40:55 -0000 Received: from minnie.tuhs.org (50.116.15.146) by inbox.vuxu.org with ESMTPUTF8; 9 Mar 2023 12:40:55 -0000 Received: from minnie.tuhs.org (localhost [IPv6:::1]) by minnie.tuhs.org (Postfix) with ESMTP id 3A86541291; Thu, 9 Mar 2023 22:40:50 +1000 (AEST) Received: from lechuck.jsg.id.au (jsg.id.au [193.114.144.202]) by minnie.tuhs.org (Postfix) with ESMTPS id 71C664128F for ; Thu, 9 Mar 2023 22:40:42 +1000 (AEST) Received: from largo.jsg.id.au (largo.jsg.id.au [192.168.1.43]) by lechuck.jsg.id.au (OpenSMTPD) with ESMTPS id 13be4af5 (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Thu, 9 Mar 2023 23:40:39 +1100 (AEDT) Received: from localhost (largo.jsg.id.au [local]) by largo.jsg.id.au (OpenSMTPD) with ESMTPA id 0c5a39ba; Thu, 9 Mar 2023 23:40:38 +1100 (AEDT) Date: Thu, 9 Mar 2023 23:40:38 +1100 From: Jonathan Gray To: Kenneth Goodwin Message-ID: References: <20230308131008.0C2D018C07B@mercury.lcs.mit.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Message-ID-Hash: 6ZJ7WQ5OIZMW3GSVUTXJYTDO5JTJ466K X-Message-ID-Hash: 6ZJ7WQ5OIZMW3GSVUTXJYTDO5JTJ466K X-MailFrom: jsg@jsg.id.au 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: Noel Chiappa , tuhs@tuhs.org 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: removed in PWB/UNIX 1.0. ifdef'd out in the Harvard/Radcliffe Student Time-sharing System (HRSTS) parts found in tuhs/Applications/Usenix_77. h/distrib.note includes: '4. "Huge" files are not supported by our modifications. This is not necessarily a hard restriction, however we early on decided we wanted no more than one level of indirection all the way up to 1 megabyte, and had no need for larger files. The incompatibilities may be minimal, but we have not even bothered to seek them out.' On Thu, Mar 09, 2023 at 03:21:19AM -0500, Kenneth Goodwin wrote: > 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 > >