Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!dali.cs.montana.edu!uakari.primate.wisc.edu!sdd.hp.com!wuarchive!udel!sbcs!umcvmb!c506634
From: c506634@umcvmb.missouri.edu (Eric Edwards)
Newsgroups: comp.arch
Subject: Re: Can old architectures run fast?
Message-ID: <c506634.3284@umcvmb.missouri.edu>
Date: 8 May 91 23:09:20 GMT
Sender: usenet@sbcs.sunysb.edu (Usenet poster)
Followup-To: comp.arch
Organization: Hackers without Hard Drives
Lines: 23

In article <1991May7.130302.22332@vlsi.waterloo.edu> ward@vlsi.waterloo.edu (Paul Ward) writes:
>  
> A meaningless question - how can you possibly compare price performance of
> a workstation (typically a single or a few user machine) with an IBM mainframe
> which can support 400+ users concurrently?  If anything, the major difference
> between PCs, workstations, minis and mainframes is the IO bandwidth, not
> the processor performance.  What good is 500 MIPS and 50 MFLOPS if you are
> waiting so long for an I/O operation to complete that the real performance is
> ~5 MIPS and 0.5 MFLOPS.  (The same applies to the memory subsystem - you have
 
It's not entirely meaningless.  Many jobs are CPU, not I/O bound. 
Compatibility aside, you would have to be a fool to use an IBM mainframe
for that.   They don't even come close to competitive with workstations on
CPU performance.  Can *all* the price performance difference be attributed
to the presence or absence of a high speed IO system?  
 
Also, is there anything to prohibit a RISC based machine from having a high
speed IO subsystem?  Would adding this make the machine cost as much as a
3090?
  
Eric Edwards:  c506634 @  "I say we take off and nuke the entire site
Inet: umcvmb.missouri.edu  from orbit.  It's the only way to be sure."
Bitnet: umcvmb.bitnet      -- Sigourney Weaver, _Aliens_