home *** CD-ROM | disk | FTP | other *** search
- Path: sparky!uunet!europa.eng.gtefsd.com!emory!gatech!darwin.sura.net!spool.mu.edu!sgiblab!rtech!amdahl!JUTS!cd.amdahl.com!jjs40
- From: jjs40@cd.amdahl.com (John Sullivan)
- Newsgroups: comp.arch
- Subject: Re: How many PC's make an Amdahl mainframe
- Message-ID: <128R02pn34lx01@JUTS.ccc.amdahl.com>
- Date: 28 Jan 93 18:52:05 GMT
- References: <1k46ioINNijv@fido.asd.sgi.com> <1993Jan26.225943.21955@enterprise.rdd.lmsc.lockheed.com> <1993@niktow.canisius.edu>
- Sender: netnews@Frobozz.COM
- Organization: Amdahl Corporation, Sunnyvale CA
- Lines: 33
-
- Our news feed missed the beginning of this thread, so I never saw the original
- posting. But, I'll toss out some numbers to kick around.
-
- Our current high-end machine is an 8-CPU shared memory symmetric
- multiprocessor. The FCS cycle time was 6.5ns, but I don't know what we are
- currently shipping them at. The CPU pipeline is capable of issuing an
- RX-format instruction every cycle, which is equivalent to a load immediately
- followed by an ALU operation. The machine holds 2GB of 25ns main storage,
- and 8GB of 80ns extended storage. It supports 4 I/O processors, each of
- which can handle up to 128 channels. Both high-speed fiber-optic and older
- parallel 370 channels are supported.
-
- I won't argue a lot about CPU performance, because our metrics are different
- from those used by the non-IBM compatible markets.
-
- As far as memory and I/O are concerned, PC's in general still can't support
- more than 16MB of RAM. A SCSI controller with DMA support provides about
- the same functionality as a mainframe I/O channel. In theory, you can put
- more than one in a PC, but the bus can't really support it at that point.
-
- So, divide 10GB by 16MB and you get something in the range of 640 PC's to
- match a mainframe on memory. If you're concerned about I/O, it'll take
- about 512 PC's to match the mainframe. I could also dig up the numbers on
- weight and power consumption, but those are too scary to think about.
-
- On a side note, someone mentioned interrupt handling capability. The IBM
- 390 architecture has complex facilities for batching up multiple interrupt
- events and distributing them across multiple CPUs. This is a major win
- when it comes to running thousands of I/O devices at the same time.
-
- --
- John Sullivan, Engineer/CPU Development | "Fools! I'll destroy them all..."
- Amdahl Corporation, Sunnyvale CA | jjs40@cd.amdahl.com, (408)746-4688
-