Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!lll-winken!decwrl!sgi!rpw3@rigden.wpd.sgi.com From: rpw3@rigden.wpd.sgi.com (Robert P. Warnock) Newsgroups: comp.arch Subject: Re: The Killer Micro From Hell [Really: fight ... Message-ID: <47800@sgi.sgi.com> Date: 9 Jan 90 10:57:11 GMT References: <34030@mips.mips.COM> <4322@nttmhs.ntt.JP> <39807@ames.arc.nasa.gov> <3101@umn-d-ub.D.UMN.EDU> <40043@ames.arc.nasa.gov> Sender: news@sgi.sgi.com Reply-To: rpw3@rigden.UUCP (Robert P. Warnock) Organization: Silicon Graphics, Inc., Mountain View, CA Lines: 52 In article <40043@ames.arc.nasa.gov> lamaster@ames.arc.nasa.gov (Xugh LaMaster) writes: +--------------- | 4) Don't hold your breath on real I/O bandwidth. The challenge will be to | put enough in there to get something reasonable out of the CPU. I think | 10-40 MBytes/sec is probably doable for KMs. Cray can get over 10MB/sec | through the filesystem on *one* 12MB/sec disk; so could a KM... +--------------- FDDI is 12.5 MB/s peak. Most KMs have some sort of FDDI board available at this point, though the throughputs are somehwat disappointing at present. However, we will see some KMs handling a full FDDI's worth of data by the end of this year, even over VME busses. But many pundits already see FDDI as "too slow" for a back-end I/O channel... The ANSI X3T9.3 HPPI-PH interface (formerly Cray "HSC") is either 125 MB/s or 250MB/s (that's "bytes", boys 'n' girls, not "bits"), depending on whether you choose the 32- or 64-bit data path. Some KMs already have HPPI interfaces which, as you might imagine, can't suck the pipe at full steam yet. By 18 months from now, that will have changed, as network and channel interfaces start speaking directly to system memory busses, bypassing traditional "I/O busses" such as VME. X3T9.3 is also looking at a Fiber Channel (FC) version of HPPI. At least two companies offer single chips *today* which take HPPI-speed 32-bit-word streams and serialize them into gigabit/sec bit-serial streams, and vice-versa. The holdup right now is affordable fiber-optoelectronics at gigabit speeds, but that will change. And in the mean time, people are considering going back to *copper* (but still bit-serial to keep the cables small) for "I/O bus" distances, since wire is still cheap. [Yes, you can run at 1 Gb/s over cheap coax, for some 10's of meters. That's about the same distance as HPPI-PH.] The X3T9.3 meeting this week is considering possible ways to glue HPPI and IPI-3 together. Fast future disks may (or may not) use IPI-3. Myself, I'd like the disks to speak HPPI-FC directly, or something equivalent. All in all, I think the KMs will have the I/O capability. It will just be a little slower in coming than we'd like, and that due more to delays in getting fast I/O devices at "KM prices" than in getting fast paths into the KMs themselves. And given HPPI (especially HPPI-FC), the idea of SC's as file servers for KMs isn't totally ridiculous... -Rob ----- Rob Warnock, MS-9U/510 rpw3@sgi.com rpw3@pei.com Silicon Graphics, Inc. (415)335-1673 Protocol Engines, Inc. 2011 N. Shoreline Blvd. Mountain View, CA 94039-7311