[kennedy]

If I do this:

longCommand < in | longCommand2 > out

on a dual processor machine, I would expect that longCommand would run on one processor and its output would be fed into longCommand2 on the other processor.

Has anyone verified that such actually happens?


(Yes, I am not sitting on a dual processor machine right now. But I am suddenly curious.)

[danengel]

Tell me what to enter in the Terminal and I'll do it for you. I just don't know with what command to feed my Dual 1.25 G4 long enough to watch `top` long enough...

[danengel]

Yes, it does use the second CPU. No wonder actually, it's just two processes which are scheduled by the OS no matter if they have a pipe in between or not.

I let a 400 MB text file full of nonsense run through a series of `sed` single-character replacement while watching `top` besides. Completely meaningless, but uses some CPU for a while:

sed -e s/a/b/ bigfile.txt | sed -e s/x/y/ | sed -e s/q/r/ | sed -e s/r/w/ | sed -e s/b/v/ > /dev/null

[kennedy]

Originally posted by danengel:
Yes, it does use the second CPU. No wonder actually, it's just two processes which are scheduled by the OS no matter if they have a pipe in between or not.

Thanks. That's what I thought; and that's how it should be. But I wanted to verify it... but didn't have a dual to run the test.

Thanks!