Path: utzoo!attcan!uunet!samsung!zaphod.mps.ohio-state.edu!mips!winchester!mash From: mash@mips.COM (John Mashey) Newsgroups: comp.arch Subject: Re: Extremely Fast Filesystems Message-ID: <40644@mips.mips.COM> Date: 7 Aug 90 14:54:10 GMT References: <5539@darkstar.ucsc.edu> <13285@yunexus.YorkU.CA> <30728@super.ORG> <13667@cbmvax.commodore.com> Sender: news@mips.COM Reply-To: mash@mips.COM (John Mashey) Organization: MIPS Computer Systems, Inc. Lines: 85 In article <13667@cbmvax.commodore.com> jesup@cbmvax (Randell Jesup) writes: >... >>This is very elegant, but there is >>a problem. We're running out of address bits again. >... > I submit that your situation is something of an unusual case, and is >likely to remain unusual for at least a decade, perhaps 2. Few machines >(percentage-wise) even have 4 GB of storage, let alone files larger that 4GB >(I've never even seen a file larger than 100MB, even on mainframes). > > Eventually, perhaps, but not in the near future. There are people >who have greater needs, that's the whole justification for the selling of >supercomputers, and the vastly expensive (read fast & large) IO systems that >support them. But they're a tiny minority, numbers-wise. Until the >number of people that require such things increases sufficiently, the only >architectures to support the extra address bits will be the super-(and maybe >mini-super-)computers. Those extra address bits are _not_ free, in silicon, >memory, etc. (I hope we haven't started the 32+ addr bit rwars again...) Well, there are always less higher-end things than lower-end ones. However, I'd STRONGLY disagree with the idea that 64-bit machines will remain confined to the super- & minisuper world for 10-20 more years. I propose instead: a) We are currently consuming address space at the rate of 1 bit year. b) Plenty of applications already exist for workstation-class machines, for which the devlopers bitterly complain that they only have 31 or 32 bits of virtual address space, regardless of how much physical address space they have. Note that they want bigger physical memories, also, of course. However, the real issue is being able to structure applications conveniently, and then slide various amounts of real memory underneath. I've participated in customer meetings (commercial, not even scientific), in which people complained seriously that some microprocessor-based machine of ours started with 256MB as maximum memory. They were more happy to know we'd get 1GB soon, but they still grumbled that it should be higher.... c) Observe that there already exist desktop workstations that support max physical memories in the 128MB - 512MB range, using 4Mb DRAMs. Hence, by the 64Mb DRAM generation, one can expect 2GB - 8GB maxes. After all, at that point, you can get 4GB or so within a 1-ft cube. Of course, such things will not be on every desktop. However, people will certainly expect the servers to be able to do such things, and they'll certainly want workstations and servers that run the same code, especially since the economics of this business mandate that a company's smaller servers be derived from the workstations. So, here's my counter-prediction to the idea that it will be 10-20 years: No later than 1995: 1) There will be, in production, 64-bit microprocessors (and I mean 64-bit integers & pointers, not just 64-bit datapaths, which micros have had for years in FP). They'll cost < $500 apiece, i.e., less than a 486 does today. They'll either be new architectures, or derivations of existing RISCs. 2) In fact, they'll be shipping in systems, in reasonable quantities. Let me try a market-analyst prediction and claim that there will be at least 50,000 such machines out there by YE1995, and 150,000 by YE1996. Now, 150,000 machines is not a huge number .... but it's rather larger than the number of supers and minisupers.... So, here's a thought to stimulate discussion: What applications (outside the scientific / MCAD ones that can obviously consume the space) would benefit from 64-bit machines? Why? (for example, here are some low-level reasons why a a particular one might benefit): a) Need more physical memory, and thus more virtual address to deal with it conveniently. b) Need more virtual memory, to address a lot of data at once, and so probably need more phyiscal memory also. c) Need more virtual memory, sometimes sparsely addressed, to use algorithms and design approaches to make the software reasoanble, but possibly with less physical memory than b). -- -john mashey DISCLAIMER: UUCP: mash@mips.com OR {ames,decwrl,prls,pyramid}!mips!mash DDD: 408-524-7015, 524-8253 or (main number) 408-720-1700 USPS: MIPS Computer Systems, 930 E. Arques, Sunnyvale, CA 94086