Why the external dos command/program is so slow in 64 bit window?

11 visualizaciones (últimos 30 días)
Zhi
Zhi el 22 de Feb. de 2011
Editada: Jan el 3 de Mayo de 2017
Hi,
I try executing some external commands/programs in Matlab (R2010a, 64bit) but they are very slow. Here is an example: Matlab program: disp('Test external command in Matlab');
for i = 1:5 tic system('cd .'); toc end
Results: Test external command in Matlab Elapsed time is 7.136996 seconds. Elapsed time is 6.094630 seconds. Elapsed time is 5.574957 seconds. Elapsed time is 6.235473 seconds. Elapsed time is 5.973438 seconds.
My computer is Dell Optiplex 980, Windows 7. I have not met the same problem in Linux or 32bit Matlab.

Respuestas (4)

Jan
Jan el 22 de Feb. de 2011
Editada: Jan el 3 de Mayo de 2017
This can depend on "cd .". If the current directory contains 7000 files and is on a network drive connected by a 100MBit ethernet, 6 seconds are not really surprising.

the cyclist
the cyclist el 22 de Feb. de 2011
I am using R2010b on a 64-bit Mac, and I do not see that behavior. My elapsed times are on the order of milliseconds.

Aviv Rosenberg
Aviv Rosenberg el 31 de Oct. de 2016
Editada: Walter Roberson el 31 de Oct. de 2016
Try this:
Haven't tested on windows, but it really speeds up my workflow on OSX.
  1 comentario
Walter Roberson
Walter Roberson el 31 de Oct. de 2016
I notice that the source does
pb.redirectErrorStream(true);
I am wondering if that affects explicit I/O redirection the user may have given on the command line, such as if the command were
someCommand SomeArguments 2>SomeOutputFile
because the user wanted stderr to go to a file?

Iniciar sesión para comentar.


Xiangrui Li
Xiangrui Li el 3 de Mayo de 2017
I observed the slowness for both win32 and win64. I just posted a question why redirecting the output to a file improve the performance. It is strange that, even if there is no output, redirecting still makes it faster.
tic, for i = 1:5, system('cd .'); end; toc
Elapsed time is 0.627796 seconds.
tic, for i = 1:5, system('cd . >myFile'); end; toc
Elapsed time is 0.111956 seconds.

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