memory xfer rates program

From: Brian Whitney (UCSD.EDU!celit!fpssun.fps.com!keeper.fps.COM!keeper)
Date: Mon Sep 30 1991 - 10:32:33 CDT


Hi,

Brian Whitney with FPS Computing.

I tried running your memory xfer program on our Model 500
SPARC series computer and came up with results that
are a little concerning to me.

First of all, the type in your program is

>>> parameter (N= 1 000 000)
>>> real a(N),b(N),c(N)
>>> real second

While in your test loop, you have a double precision constant.
This will cause extra operations in FORTRAN, consisting of type
conversions.

>>> do 30 j=1,N
>>> c(j) = 3.0d0*a(j)
>>> 30 continue

I believe you meant to have code run in 64-bit precision, because
results I achieved would say that is the case.

When I changed the Real declartion to real*8, the results look
correct to me for our machine.

Here are results for the FPS S511, SPARC based cpu with added vector
processor.

Code as presented...

systst2% x.x.
Timing calibration ; t = 6.45360 clicks
    
Assignment: Rate = 247.924 MB/s MFLOPS = 0.
Scaling: Rate = 102.594 MB/s MFLOPS = 6.41215
Summing: Rate = 186.564 MB/s MFLOPS = 7.77351
SAXPYing: Rate = 127.367 MB/s MFLOPS = 10.6139

Code modified to make 3.0d0 -> 3.0 (pure 32 bit run, I believe the
Mbyte calculation is 2x what it should be...)

systst2% x.x
Timing calibration ; t = 6.53050 clicks
    
Assignment: Rate = 245.004 MB/s MFLOPS = 0.
Scaling: Rate = 169.176 MB/s MFLOPS = 10.5735
Summing: Rate = 186.296 MB/s MFLOPS = 7.76235
SAXPYing: Rate = 185.753 MB/s MFLOPS = 15.4794

Code modified to have real -> real*8 (mbytes should be correct)

systst2% x8.x
Timing calibration ; t = 6.42171 clicks
    
Assignment: Rate = 249.155 MB/s MFLOPS = 0.
Scaling: Rate = 168.101 MB/s MFLOPS = 10.5063
Summing: Rate = 188.048 MB/s MFLOPS = 7.83534
SAXPYing: Rate = 189.218 MB/s MFLOPS = 15.7681

The last data are math library routines replacing your loops.
This just shows closer to what the limits of the machine are...

systst2% x2.x
Timing calibration ; t = 6.45340 clicks
    
Assignment: Rate = 247.931 MB/s MFLOPS = 0.
Scaling: Rate = 245.912 MB/s MFLOPS = 15.3695
Summing: Rate = 241.687 MB/s MFLOPS = 10.0703
SAXPYing: Rate = 244.302 MB/s MFLOPS = 20.3585

Brian Whitney
FPS Computing
3601 SW Murray Blvd
Beaverton, OR 97005

(503) 641-3151 x2682
keeper@fps.com



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