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Re: Terminal output from ssh much slower than putty


Cygwin's "terminal" I/O speed varies considerably depending on two primary and independent choices: Console (Windows character subsystem) vs. RXVT and CYGWIN with vs. without "tty".

In my home directory:

% find |wc -l

% find -type d |wc -l

% find -type f |wc -l

Console w/o CYGWIN=tty: % time /bin/ls -lRF

real    0m17.703s
user    0m0.733s
sys     0m3.874s

Console w/ CYGWIN=tty % time /bin/ls -lRF

real    0m37.150s
user    0m0.561s
sys     0m4.062s

RXVT w/o CYGWIN=tty % time /bin/ls -lRF

real    0m4.964s
user    0m0.702s
sys     0m3.827s

RXVT w/ CYGWIN=tty % time /bin/ls -lRF

real    0m4.864s
user    0m0.515s
sys     0m3.999s

I made several "priming" runs before capturing this timing information.

This test emphasizes scrolling speed, I believe. I think RXVT uses an algorithm that skips ahead when large volumes of output are being produced. This produces faster results (with the same end product on the screen--it's just the scrolling that skips ahead) but the visual appearance is discernibly less "continuous" than is the console mode.

So, if raw output speed as characterized by scrolling is the issue, use RXVT. If your criteria are different (say, cursor addressing as characterized by Emacs, Vim or Info), then I'd do some tests on your own to find out what works best for you.

Note, too, that for some applications, most notably Emacs, you _must_ set the "tty" option in the CYGWIN environment variable. This maximizes Unix tty compatibility. That option clearly imposes a much bigger performance hit in the Windows console than in RXVT.

Randall Schulz

At 05:55 2003-03-05, Erik Vigmostad wrote:
Is there some way to speedup the output to my terminal? I would like to use cygwin for ssh'g to various servers, but it is so much slower that using putty that I can't.

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