Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!utgpu!water!watnot!watmath!clyde!rutgers!brl-adm!seismo!rochester!pt.cs.cmu.edu!cadre!pitt!cisunx!dpl
From: dpl@cisunx.UUCP
Newsgroups: comp.unix.wizards
Subject: Vax 86xx FBOX decision
Message-ID: <3431@cisunx.UUCP>
Date: Tue, 24-Mar-87 19:47:36 EST
Article-I.D.: cisunx.3431
Posted: Tue Mar 24 19:47:36 1987
Date-Received: Sat, 28-Mar-87 05:33:10 EST
Reply-To: dpl@cisunx.UUCP (Dave P. Lithgow)
Distribution: world
Organization: Univ. of Pittsburgh, Comp & Info Sys
Lines: 40

Un*x/Ultrix Vax users:

	One of our vaxes (Vax 8650, Ultrix-32 V1.2) was ordered without
an F-BOX floating point accelerator, under the mistaken belief that
only our VMS users would be involved in number crunching.  Thus, I am
now trying to justify the acquisition ($19,600 + $665 installation charge =
$20,265.00) of a DEC 8650 F-BOX.

I asked DEC support (a biased source): 
	'What would an F-BOX do for a un*x user?'
DEC's response: 
	'all compiles would be sped up by 50%, because the link
	editor uses floating point to calculate virtual addresses.'

Can anyone verify this?

For non-wizards: 
	(1) ld (link editor) is invoked during compiles which
  complete without errors, in order to link in referenced routines, and
  create an executable file.
	(2) The FBOX of an 8600 is exactly the same as the FBOX of an 8650.

System workload characterization:
	This vax is in an academic situation, with aboout 2000 accounts,
70% of which are students learning pascal, lisp, C, ada, data structures,
simulation, etc.  The remaining 30% crunch numbers and process tapes.
The machine is quite often CPU constrained, running for hours at a time at
0% idle.  Therefore, even if DEC is off by 100%, a mere 25% overall speedup
in compiles might be worth the expense ...

	Is there a way to collect instruction frequency distribution
statistics?  Remember, if a program has just 5 floating point
instructions, if those five comprise 10% of the instructions executed
by a utility (due to their being inside an important loop), then the
execution profile will be very different from the frequency distribution
of floating point instructions in the executable file.  Thus, I there's
no point to writing a program to count the number of flt. pt. instructions
in all the most used utilities...

							-Dave
David P. Lithgow		Sr. Systems Analy./Pgmr., Univ. of Pittsburgh
USENET:  {allegra,bellcore,ihpn4!cadre,decvax!idis,psuvax1}!pitt!cisunx!dpl
CCnet(DECnet): CISVM{123}::DPL,CISVXO::DPL (I admit it: I'm a unix and VMS) 
Bitnet(Jnet):  psuvax1!dpl@pittvms.bitnet    ( systems programmer too)
ARPA: (via UUCP) pitt!cisunx!dpl@cadre.arpa
ARPA: (via Bitnet) DPL%PITTVMS.BITNET@WISCVM.WISC.EDU
CSNET: dpl%pitt@csnet-relay