Path: ...!news.iecc.com!.POSTED.news.iecc.com!not-for-mail From: John Levine Newsgroups: comp.arch Subject: Re: Architectural implications of locate mode I/O Date: Thu, 1 Aug 2024 21:01:12 -0000 (UTC) Organization: Taughannock Networks Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Injection-Date: Thu, 1 Aug 2024 21:01:12 -0000 (UTC) Injection-Info: gal.iecc.com; posting-host="news.iecc.com:2001:470:1f07:1126:0:676f:7373:6970"; logging-data="6259"; mail-complaints-to="abuse@iecc.com" In-Reply-To: Cleverness: some X-Newsreader: trn 4.0-test77 (Sep 1, 2010) Originator: johnl@iecc.com (John Levine) Bytes: 2571 Lines: 33 According to Stephen Fuld : >On 7/31/2024 6:41 PM, Lawrence D'Oliveiro wrote: >> On Sat, 6 Jul 2024 06:15:56 -0000 (UTC), Stephen Fuld wrote: >> >>> As you posted below, the whole PDS search stuff could easily be a >>> disaster. Even with moremodest sized PDSs, it was inefficient has >>> hell. >> >> Would locate mode have helped with this? > >No. The problem was that the PDS search was a linear search of records >on the disk drive i.e. typically multiple disk revolutions), and >furthermore, it required (until the fast PDS search came along) that the >host channel take action on each disk record checked, even the ones that >didn't match, including resending the search argument to the disk >controller. > >This has nothing to do with locate mode. He's made it painfully clear that he doesn't understand the relative speed of CPUs and disks, or the costs of multiple I/O buffers on systems with small memories, particularly back in the 1960s when this stuff was being designed. Nor how records in COBOL data divisions were designed so implementations could read and write file records directly from and to the buffers, and the IOCS of the era enabled that in COBOL and other languages. Perhaps this would be a good time to stop taking the bait. I thought this silly argument was over a month ago. -- Regards, John Levine, johnl@taugh.com, Primary Perpetrator of "The Internet for Dummies", Please consider the environment before reading this e-mail. https://jl.ly