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Re: min function very slow?
From: |
Dmitri A. Sergatskov |
Subject: |
Re: min function very slow? |
Date: |
Sat, 29 Jan 2005 23:51:41 -0700 |
User-agent: |
Mozilla Thunderbird 0.9 (X11/20041127) |
Daniel J Sebald wrote:
Dmitri A. Sergatskov wrote:
Daniel J Sebald wrote:
Thank you... so do you think your increase for mintime is a blip in
the OS? Yours is a factor of 4.5 difference, mine is a factor of 76.
I do not understand this at all. More over on my other computer
(AthlonXP 1666 MHz)
the mintime is 2 seconds... The same OS etc...
So I'm not dreaming. :-)
I put a script in my path to redefine min(x) as -max(-x). That gets me
down to the numbers your quoting. I'll see if I can run a profiler on
this. I don't think it is in dNDArray.cc where it is spending its time.
I rewrote your script as a function (attached). Here is some numbers:
octave:1> [loopt,mint,maxt]=mmt(10000)
loopt = 0.040803
mint = 0.19301
maxt = 0.22110
octave:2> [loopt,mint,maxt]=mmt(10000)
loopt = 0.031585
mint = 0.18326
maxt = 23.859
octave:3> [loopt,mint,maxt]=mmt(10000)
loopt = 0.039405
mint = 0.18089
maxt = 22.695
On SMP computer (octave compiled with -lpthread, otherwise the same flags):
octave:1> [loopt,mint,maxt]=mmt(10000)
loopt = 0.033668
mint = 0.15524
maxt = 0.18152
octave:2> [loopt,mint,maxt]=mmt(10000)
loopt = 0.026402
mint = 0.14753
maxt = 2.6565
As you can see the first time it runs it gets reasonable numbers, after that it
goes nuts.
Dan
Dmitri.
function [looptime,maxtime,mintime]=mmt(N_loop)
tic();
for i=1:N_loop
j = i;
end
looptime = toc();
for i=1:N_loop
j = max(i);
end
maxtime = toc() - looptime;
for i=1:N_loop
j = min(i);
end
mintime = toc() - maxtime;
endfunction
- min function very slow?, Daniel J Sebald, 2005/01/29
- Re: min function very slow?, Dmitri A. Sergatskov, 2005/01/29
- Re: min function very slow?, John W. Eaton, 2005/01/30
- Re: min function very slow?, Dmitri A. Sergatskov, 2005/01/30
- Re: min function very slow?, John W. Eaton, 2005/01/30
- Re: min function very slow?, Daniel J Sebald, 2005/01/30
- Re: min function very slow?, Daniel J Sebald, 2005/01/30
- Re: min function very slow?, Daniel J Sebald, 2005/01/30
- Re: min function very slow?, John W. Eaton, 2005/01/30