Re: Slowup in 2.1.54

[Dmitri A. Sergatskov]

David Bateman wrote:

> The gcd stuff might just be a timing error. The code used for the timing
> in the sciview tests is pretty rough, using tic/toc. I've replaced this
> in my version using cputime instead. and get the follow

cputime does not work with pthreads, so I have to use tic/toc.
Here is another example of recursion slowdown:

2.1.53:

tic; for n=1:1000; bm_x=sylvester_matrix(7) ; endfor ; toc
ans = 4.2025

2.1.54:

tic; for n=1:1000; bm_x=sylvester_matrix(7) ; endfor ; toc
ans = 11.574

(those are both stock releases no patches for SMP/pthreads etc...;
--enable-shared --disable-static ; -O3 -march=athlon-mp; AthlonMP x2)


> So the only significant slow up I see is in the last test. Here is another
> interting set of tests
>
> 2.1.50
>  tic; x = []; for i=1:1e3; x = [x, i]; endfor; toc 
> ans = 0.079843
> tic; x=0; for i=1:1e3; x++; endfor; toc  
> ans = 0.018920

I do not trust tic/toc numbers less then 0.1 sec. So I increased the index:

2.1.53:

tic; x = []; for i=1:1e4; x = [x, i]; endfor; toc
ans = 3.2951

2.1.54:

tic; x = []; for i=1:1e4; x = [x, i]; endfor; toc
ans = 20.234



2.1.53:

tic; x=0; for i=1:1e4; x++; endfor; toc
ans = 0.024073
tic; x=0; for i=1:1e5; x++; endfor; toc
ans = 0.24130
tic; x=0; for i=1:1e6; x++; endfor; toc
ans = 2.3381

2.1.54:

tic; x=0; for i=1:1e4; x++; endfor; toc
ans = 0.028044
tic; x=0; for i=1:1e5; x++; endfor; toc
ans = 0.26263
tic; x=0; for i=1:1e6; x++; endfor; toc
ans = 2.6506


(I do not understand it, but my old records show that loops
were slower, it seems that something else in my system changed that
speeded it up.)

> Regards
> David

Sincerely,
Dmitri.