Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!lll-winken!uunet!mcsun!hp4nl!sara5!toon From: toon@news.sara.nl Newsgroups: comp.arch Subject: Re: Incremental sync()s and using disk idle time Message-ID: <1991Mar14.181022.2824@news.sara.nl> Date: 14 Mar 91 17:10:21 GMT References: <28975@cs.yale.edu> <1991Mar12.202238.19586@zoo.toronto.edu> Lines: 41 In article <1991Mar12.202238.19586@zoo.toronto.edu>, henry@zoo.toronto.edu (Henry Spencer) writes: > In article > kinch@no31sun.csd.uwo.ca (Dave Kinchlea) writes: >>... it would be highly advantagous (in the general case) to take all of >>the filesystem information out of the kernel and give it to the I/O controller. > > Which filesystem? System V's? That's what you'd get, you know... > Actually, it sounds more like the CDC Cyber 6600 .. 170 series: one or two CPU's and 10 to 20 Peripheral Processors, the latter designed to do the I/O in broad sense (handling all from disk block assignment to actual channel I/O). > That aside, the most probable result is that your big expensive main host > CPU, which could undoubtedly run that code a lot faster, will spend all > its time waiting for the dumb little I/O controller to run the filesystem. > This is not a cost-effective use of hardware resources. In the Cyber series this was 'solved' by assigning the compute intensive parts to the CPU (e.g.: converting Record Block Number (logical disk block) to cylinder/track/sector triples v.v.) > > [Incidentally, is there some reason why twits (or readers written by twits) > keep saying "Followup-To: comp.protocols.nfs", when this topic is only > marginally related to NFS and highly related to architecture? It's quite > annoying to have to keep manually fixing this.] I don't know. IMHO performance problems of NFS are of a far different nature - think of all your I/O spread over 512 byte UDP packets and the interrupt rate this generates on your favorite U*X system (can you say: Cray Y-MP ?) > -- > "But this *is* the simplified version | Henry Spencer @ U of Toronto Zoology > for the general public." -S. Harris | henry@zoo.toronto.edu utzoo!henry -- Toon Moene, SARA - Amsterdam (NL) Internet: TOON@SARA.NL /usr/lib/sendmail.cf: Do.:%@!=/