You (John D. McCalpin) write:
>
> On Thu, 28 Oct 1993, Bo Thide' wrote:
>
> > I have had a closer look at the code and see that one must either
> > increase n or use another timing technique. I now see that the ntimes
> > parameter does not affect the clock granularity.
>
> It does not affect the timing directly, but it does allow averaging
> over more ticks. I am not convinced that the answers are the same as for
> timing the larger segment separately, but it is the best that can be done
> if memory is limited.
>
I just rebuilt my 720 kernel with a four times larger stack size and
increased the n parameter a bit. Here are the new HP9000/720 results:
--------------------------------------
Single precision appears to have 7 digits of accuracy
Assuming 4 bytes per default REAL word
--------------------------------------
Timing calibration ; time = 118.0 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: 44.4446 .3650 .3600 .3700
Scaling : 47.0589 .3400 .3400 .3400
Summing : 48.0001 .5020 .5000 .5100
SAXPYing : 52.1739 .4650 .4600 .4700
--------------------------------------
Double precision appears to have 16 digits of accuracy
Assuming 8 bytes per DOUBLEPRECISION word
--------------------------------------
Timing calibration ; time = 114.0000076964497 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: 48.4849 .3330 .3300 .3400
Scaling : 50.0000 .3260 .3200 .3300
Summing : 50.0000 .4810 .4800 .4900
SAXPYing : 53.3335 .4560 .4500 .4600
As I see it, the best way would be to implement a timing routine based on
gettimeofday. On the HP9000/700 this timer has a 1 microsec resolution.
The etime timer has a 10 millisec resolution.
Bo
-- ^ Bo Thide'---------------------------------------------Science Director- |I| Swedish Institute of Space Physics, S-755 91 Uppsala, Sweden |R| Phone: (+46) 18-303671. Fax: (+46) 18-403100. IP: 130.238.30.23 /|F|\ INTERNET: bt@irfu.se UUCP: ...!mcvax!sunic!irfu!bt ~~U~~ ----------------------------------------------------------------sm5dfw-
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