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From: tim@proton.amd.com (Tim Olson)
Newsgroups: comp.sys.hp,comp.benchmarks
Subject: Re: 68040 and Floats, is this true?
Message-ID: <1991Jun14.195033.28799@dvorak.amd.com>
Date: 14 Jun 91 19:50:33 GMT
References: <TT.91Jun9113646@euler.jyu.fi> <3286@sparko.gwu.edu> <2080@kuling.UUCP>
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Reply-To: tim@amd.com (Tim Olson)
Organization: Advanced Micro Devices, Austin, TX
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In article <2080@kuling.UUCP> bt@irfu.se (Bo Thide') writes:
| In order to see how well the 68040 performs in general, and on sprintf()
| in particular, I ran the "C Cost" benchmark on the HP9000/425t (68040/25
| MHz), HP9000/400t (68030/50 MHz) and the Sun SparcStation 1.  The
| results are presented below.  As is seen, the HP-UX 7.05 sprintf() on
| the 68040 is a factor of 2 *slower* than on the 68030 but a factor of
| two *faster* than in SunOS4.1 on the Sun SparcStation (lower numbers =
| faster).

I don't trust any of these numbers, as they appear highly suspect for
even the simple operations:

| RESULTS:
| 
| -------------------------------------------------------------
| Operation                         Mics/N  Mics/N  Mics/N
|                                   HP425t  HP400t  Sun Sparc-
|                                   (68040) (68030) Station 1
| Null Loop (n=1000000)           
|  {}                                 0.00    0.43    0.18
				      ^^^^
				      It appears that the HP compiler
				      removed the null loop through
				      dead code elimination.	

| Int Operations (n=1000000)              
|  i1++                               0.16    0.18    0.34
|  i1 = i2                            0.16    0.19    0.35
|  i1 = i2 + i3                       0.24    0.35    0.30
|  i1 = i2 - i3                       0.24    0.35    0.30
|  i1 = i2 * i3                       0.36    1.21    0.30
|  i1 = i2 / i3                       2.02    2.11    0.31
|  i1 = i2 % i3                       2.02    2.12    0.30

Are these register or memory operations (they would appear to be
memory to memory by the times listed)?  Note that the SparcStation
times for multiply and divide are the same as those for the simple
operations, even though it has no hardware MUL or DIV.  In the 68040
column, why does it take the same amount of time to perform an
assignment as it does to increment a variable?  That could only be
if they were register-to-register operations, but then why would it
take 160ns @ 25MHz? Again, these numbers are highly suspect.

| Control Structures (n=1000000)          
|  if (i == 5) i1++                   0.28    0.27    0.12 <-- ??
|  if (i != 5) i1++                   0.38    0.39    0.67 <-- ??
|  while (i < 0) i1++                 0.32    0.18    0.12
|  i1 = sum1(i2)                      0.20    0.82    0.60
|  i1 = sum2(i2, i3)                  0.28    1.11    0.67
|  i1 = sum3(i2, i3, i4)              0.32    1.42    0.84

How can these vary by such a large amount?  They should be equal times.

--
	-- Tim Olson
	Advanced Micro Devices
	(tim@amd.com)