🚀 go-pugleaf

(Apologies for the repost, but this apparently didn't get as far as it
should have.)

Summary of responses to my posting regarding multi-user benchmarks, and
the feasibility of replacing some of the services offered by a VMS-based
MicroVAX II with (say) a SPARCstation 1 running (say) 6 simultaneous
users at peak load.

I have retained the authors words, just edited out repeated or less
important information.

------
>From: chris@yarra.oz

MUSBUS is a UNIX benchmark - no way to run it under VMS. Same is with
AIM to my knowledge but I have no practical experience with it.

... AIM 2 has several fundamental flaws ...
AIM 3 is much better. ...

MUSBUS is in public domain and you can easily obtain the source code
to run it yourself. You can also easily customise it in the sense
of changing your job mix to reflect your real expected load.  ...

The benchmark is also a good tool for shaking and checking quality of UNIX
ports. You just increase and increase load and wait when it breaks.
Some architectures and UNIX ports are known to break supprisingly easy
above 64 simulated users.
By the way to really test a machine you should run the benchmark way
past the saturation ankle on CPU utilization and elapsed time degradation
curves. I suggest that you run it up to the number of simulated users
yielding elapsed time degradation value of at least 2.5. ...
Many a hardare vendor will only publish results on the linear section of
the curves which is pretty much useless for the purpose of assessing
where the machine saturates and how severely.

Chris Jankowski     chris@yarra.oz       chris@yarra.oz.au
Pyramid Technology Australia - Melbourne

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>From: khb@Sun.COM

Personally I think MUSBUS and AIM are nice but misguided. ...

No one in their right mind buys a DS3100 or a SS-1 as a multiuser
machine. Neither has the IO bandwidth, or any of the other goodies
that dominate in real multiuser designs. But then I think of the
Convex C120 as an adequate single user machine.

			    ... The old mainframes had 1MIPS of CPU
power, but could handle 100 users. The fact that there were dozens of
minicomputer class machines (PP's, channel controllers, etc) made this
"magic possible". A workstation is designed (primarily) to handle a
single person quite well. DS3100 and SS-1 rely on SCSI IO. SS-1 has a
buss, so it is theorectically possible to have more suitable IO for a
server, but it seems unlikely that an IPI device will be made
available:> The better solution is to buy a machine designed to be a server.

VMS is more efficient about sharing resources than unix. ...

	     ...  Single user machines are optimized to handle a few
context switches quite fast. Serious multiuser machines face 100's or
1000's of context switches a second ... hence different MMU designs
are called for (among other considerations, like IO). ...

Keith H. Bierman	Marketing Technical Specialist    ! kbierman@sun.com

------
>From: rnovak@mips.com

		... AIM and Neal Nelson are proprietary benchmarks.  You
typically have to pay large fees to see results from these benchmarks (or
whisper in your salesman's ear).

MUSBUS is probably the best, but I haven't had a chance to run that on the
M/120 yet. ...

Keep your ear to the ground about SPEC.

Robert E. Novak                                     MIPS Computer Systems, Inc.

------
>From: mash@mips.com
				...  If you look at MIPS Magazine
over the last few months, here is some (albeit not great) data on
mulit-user performance.  ALso, UNIX Review magazine's Tested Mettle
reports include multi-user, and so do Digital Reviews.

Note that the SS1 is 12 Dhrystone-mips, not VUPS.
It's more like 9 VUPS.

In the past, execution of kernel code is not something that Sun-4s
have excelled at, due to a) use of virtually-tagged caches that
needto be flushed more often than you'd like. b) register windows
not matching the way the kernel works, and (minor) c) cost of saving
large register file.

john mashey	mash@mips.com

------

As a rejoinder, and perhaps to elicit further comment, we are proposing
to provide the RISC workstation as a *supplementary* service to the MVII,
primarily for heavy CPU users (the MVII is charged for on a CPU-second
basis). 

Given that in the first instance access to the workstation will be
through ASCII terminals (perhaps some TEK4014 emulators) over ethernet
(a TCP/IP capable terminal server), I suggest that the total cpu load
may be not too much more than a single intensive user can apply using
multiple active windows.

If this is the case then the problem boils down to one of context
switching - a single user cannot be typing into several windows at any
one time. Analyzing the situation though, 6 users all typing together
would result in a peak in the order of 50 (?) context switches per
second, surely within the capability of a 12-16 (integer) MIPS
processor? 
-- 
Ray Brownrigg			domain: ray@dsiramd.dsir.govt.nz
Applied Maths Div, DSIR		ACSnet:	ray@dsiramd.nz[@munnari]
PO Box 1335			System:	OLIVETTI/AT&T 3B2/400B+, System V R3.0
Wellington, New Zealand			"unx -rules -OK"