Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!rutgers!sri-spam!ames!pioneer!lamaster From: lamaster@pioneer.arpa (Hugh LaMaster) Newsgroups: comp.arch Subject: Re: 64 Vs 32 Message-ID: <784@ames.UUCP> Date: Mon, 16-Mar-87 20:42:46 EST Article-I.D.: ames.784 Posted: Mon Mar 16 20:42:46 1987 Date-Received: Tue, 17-Mar-87 05:37:00 EST References: <3810013@nucsrl.UUCP> <985@rpics.RPI.EDU> <1310@ucbcad.berkeley.edu> Sender: usenet@ames.UUCP Reply-To: lamaster@pioneer.UUCP (Hugh LaMaster) Organization: NASA Ames Research Center, Moffett Field, Calif. Lines: 50 Keywords: address space size In article <1310@ucbcad.berkeley.edu> faustus@ucbcad.berkeley.edu (Wayne A. Christopher) writes: : > >What we need to ask is, who will need more than ~1G of memory? I think >the only applications that currently could use this much memory are >scientific programs that run on Crays (which I think are addressible to >the 64-bit word anyway). I certainly haven't been running into the 1G >limit too often lately. > There could be other applications besides the often mentioned scientific and graphics programs which could potentially benefit from machines with larger address spaces. Consider database applications, for example. Some sites have hundreds of 3380 disk drives holding databases. Currently, there is no way to address more than about one disk worth (3380's are 2.5-5.0 GB) in IBM's 32 bit address space. With a 64 bit address space, the entire disk farm could be addressed. All this data need not be accessed at one time in order to justify doing this: there are efficiency improvements in access time which would be expected by using the pager as the access method. There may be other applications which would justify the use of a large address space. The proper metric to use is the size of the system secondary storage. The virtual address space should be big enough to encompass the size of secondary storage in a virtual memory world. I know of one system that allows virtual memory to be kept on tape as well as disk (obviously the access time is slower, but the entire memory segment is restored once an access is made; efficient). At a minimum, the size of the largest OBJECT should fit in the address space, and this object may be a database, a process address space for an engineering, scientific, or graphical program, or other applications. What other applications or objects have people encountered that needed more than 1 GB? Since today there are deskside servers available for 4 MIPS workstations with 560 MB on a disk, I don't think the day is far off when even "small" systems may find the 32 bit limit a burden. I foresee a rosy future for the company which chooses to start developing its 64 bit systems now in anticipation of that future. Hugh LaMaster, m/s 233-9, UUCP {seismo,topaz,lll-crg,ucbvax}! NASA Ames Research Center ames!pioneer!lamaster Moffett Field, CA 94035 ARPA lamaster@ames-pioneer.arpa Phone: (415)694-6117 ARPA lamaster@pioneer.arc.nasa.gov "In order to promise genuine progress, the acronym RISC should stand for REGULAR (not reduced) instruction set computer." - Wirth ("Any opinions expressed herein are solely the responsibility of the author and do not represent the opinions of NASA or the U.S. Government")