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From: caf@omen.UUCP
Newsgroups: comp.sys.m68k,comp.sys.intel
Subject: Re: 386 vs 020 and big benchmarks (sieve)
Message-ID: <523@omen.UUCP>
Date: Sat, 18-Apr-87 07:17:13 EST
Article-I.D.: omen.523
Posted: Sat Apr 18 07:17:13 1987
Date-Received: Sun, 19-Apr-87 11:49:39 EST
References: <930@intsc.UUCP> <513@omen.UUCP> <933@intsc.UUCP>
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Organization: Omen Technology Inc, Portland Oregon
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Xref: utgpu comp.sys.m68k:342 comp.sys.intel:145

In article <933@intsc.UUCP> tomk@intsc.UUCP (Tom Kohrs @fae) writes:
:> :Show me a benchmark that does not fit in 256 bytes thats even keeps up
:                                            ^^^^^^^^^  (note for ref.)
:> :with at 16MHz 386.  386's are now shipping at 20MHz for the speed freaks.
:> :25MHz soon.
OK, here's one that may not fit in 256 bytes.

time bc <<f
2 ^ 4096
f

Make bct executable.  Clear the screen (no scrolling please). Then run it.

Real Time	System/comments (ws = wait state(s))

0:03.6		Amdahl 580 3 users 2/86 ames!aurora!eugene
0:06.6		Gould UTX32 6/84
0:07.6		Vax 8600 running 4.3BSD Beta, 16 Feb 1986
0:09.5	u	Sun 3/260 68020 "25 Mhz" BSD 4.3	Unix-EXPO 10/86
0:14.5	u	HP 9000/840  Spectrum RISC HP-Unix	Unix-EXPO 10/86
0:15		DG/UX 2.01, DG MV/10000SX, 8MB
0:15.7	u	Compaq 386      80386 Xenix 5	Unix-EXPO 10/86
0:15.8	u	Computer Dynamics 18mHz 386 SCO SYSV 2.2 3/87 (1)
0:20		Computer Dynamics 18mHx 386 Toolkit (16 bit bc/dc) 12/86  (1)
0:17.6	u	Corvus 386      80386 Xenix 5	Unix-EXPO 10/86

The Gentleman from Intel claims siev has a "hot spot" that fits within the
256 byte 68020 cache.  Close, but no cigar.  Those triple wait states
on writes are for references within the cache?  Don't tell us Unix 5.3 for
the 386 is using self modifying code.  So even within that inner loop,
a significant portion of memory references do not fall within the cache.

:  3.0	.6      .59     .59      ?      Intel 310/386 16MHz Unix V.3 rcc  4/16
                                ^^^

Please do the following:
	cc -O -c siev.c
	size siev.o
and report the results.

Actually, siev is a 15k program on Xenix (text+data).  Presumably much of that
15k actually gets executed, perhaps 10k.

Now Nroff and troff are larger than 15k, but they still might have hot
spots that benefir from the 68020 instruction cache the way siev and dc
appear to.  The 68020's cache won't help much with a 10 MB program which
references every memory location in succession, but then the demand paging
would be thrashing so badly one wouldn't notice instruction speed anyway.

So, how about this test:

yes "Hello World"|sed 10000q |time sort >/dev/null

Let's hear some times for 68020 with and without the cache,
also for 386 boxes.