RE: memory Bandwidth

From: Donald McLachlan (don@mars.dgrc.doc.ca)
Date: Wed Nov 06 1991 - 09:04:57 CST


Following up on our earlier correspondance ...

I have redone my testing of stream_s.f and stream_d.f and still believe
the numbers shown in your table are incorrect for a Sun SS1.

I have used script which explains all the ' 's.

Don

... Here are my results ...

Script started on Wed Nov 6 09:57:24 1991
jack don> f77 -cg89 -dalign -f -fast -O4 -native stream_s.f -o stream_s
f77: Warning: -O4 overwrites previously set optimization level of -O2
stream_s.f:
 MAIN stream:
        second:
        realsize:
        dummy:
jack don> stream_s
--------------------------------------
 Single precision appears to have 7 digits of accuracy
 Assuming 4 bytes per default REAL word
--------------------------------------
Timing calibration ; time = 177.000 hundredths of a second
Increase the size of the arrays if this is <30
 and your clock precision is =<1/100 second
---------------------------------------------------
Function Rate (MB/s) RMS time Min time Max time
Assignment: 10.5263 0.3850 0.3800 0.3900
Scaling : 9.3023 0.4370 0.4300 0.4400
Summing : 10.1695 0.5960 0.5900 0.6000
SAXPYing : 10.1695 0.5991 0.5900 0.6200
 Note: this program was linked with -fast or -fnonstd
 and so may have produced nonstandard floating-point results.
 Sun's implementation of IEEE arithmetic is discussed in
 the Numerical Computation Guide.
jack don> f77 -cg89 -dalign -f -fast -O4 -native stream_d.f -o stream_d
f77: Warning: -O4 overwrites previously set optimization level of -O2
stream_d.f:
 MAIN stream:
        second:
        realsize:
        dummy:
jack don> stream_d
--------------------------------------
 Double precision appears to have 16 digits of accuracy
 Assuming 8 bytes per DOUBLEPRECISION word
--------------------------------------
Timing calibration ; time = 210.99999696016 hundredths of a second
Increase the size of the arrays if this is <30
 and your clock precision is =<1/100 second
---------------------------------------------------
Function Rate (MB/s) RMS time Min time Max time
Assignment: 12.6316 0.3900 0.3800 0.4000
Scaling : 12.0000 0.4030 0.4000 0.4100
Summing : 12.6316 0.5740 0.5700 0.5800
SAXPYing : 11.4286 0.6350 0.6300 0.6400
 Note: this program was linked with -fast or -fnonstd
 and so may have produced nonstandard floating-point results.
 Sun's implementation of IEEE arithmetic is discussed in
 the Numerical Computation Guide.
jack don> ^D
script done on Wed Nov 6 10:07:24 1991



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