Re: Slow performance on Linux

[John L Daschbach]

>>>>> "Evan" == Evan Thomas <address@hidden> writes:

    Evan> I have recently installed octave-1.1.1 on a PC-pentium/133
    Evan> and a Sun SPARC station 2, both with 32Mb memory. Published
    Evan> benchmark figures and my own experience would suggest that
    Evan> the PC should be significantly faster than the Sun. However
    Evan> the opposite is true. In fact, for the calculations I've
    Evan> been doing, the Linux machine is unusable (almost as if it
    Evan> wasn't using the floating point unit(?)).

    Evan> Is this what I should expect or have I configured/done
    Evan> something wrong?

    Evan> The system is Linux kernel 1.3.72 on top of a Debian 0.93R6
    Evan> distribution. I've tried the both the binary and source
    Evan> distributions of octave.

I think clearly you have done something wrong.  I have not tried it
with Linux, but it runs very well on my 486/33 16M with OS/2 and my
P120 16M with OS/2.  

It runs a lot faster on a RS6000/590 256M :-)

Actually, seat of the pants benchmarks on the RS6000 seem pretty
good. Have not checked, but the matrix inversion times seem about a
factor of 2 or a little more off from Fortran, which seems pretty
good.  

It might be useful to compile a set of Octave benchmarks, both to
compare machines and compilers.  

I compiled this some time ago, but I think it's gcc 2.7.2 and the IBM
f77 compiler. For my work, the times are fine.  I'll try some on a PC
with OS/2 and send them along.


[d3h486]:(17)>tic;foo=rand(128,128);toc
ans = 0.060529
[d3h486]:(18)>tic;bar=inv(foo);toc      
ans = 0.083243
[d3h486]:(19)>tic;foo=rand(256,256);toc 
ans = 0.22873
[d3h486]:(20)>tic;bar=inv(foo);toc      
ans = 0.62577
[d3h486]:(21)>tic;foo=rand(512,512);toc 
ans = 0.89869
[d3h486]:(22)>tic;bar=inv(foo);toc      
ans = 4.8428
[d3h486]:(23)>tic;foo=rand(1024,1024);toc
ans = 3.5915
[d3h486]:(24)>tic;bar=inv(foo);toc        
ans = 36.425
[d3h486]:(31)>tic;foo=rand(2048,2048);toc 
ans = 14.634
[d3h486]:(32)>tic;bar=inv(foo);toc        
ans = 285.83


-John