[ale] compiled system calls versus shell scripts

[Jeff Hubbs]

On Thu, 2003-10-23 at 13:19, Geoffrey wrote:
> Jeff Hubbs wrote:
> 
> > I think the speedup comes from the fact that if everything is done
> > serially, you can't sneak in some computing amongst disk i/o waits, for
> > instance.  The objective seems to be to let the kernel and its MM to
> > make the best of the barrage.
> 
> Okay, call it ignorance.  How is the parallel make process any different 
> then say:
> 
> foo & bar
> 
> At the shell level 'foo & bar' run parallel.


Excellent question.  I think the answer is that the make -j parameter serves 
to limit things.  Beyond a certain point, firing off too many things at once 
probably starts to hurt more than help, mostly because of disk I/O.  By using 
make -j, you've got a way to tweak the proceedings - find a number that's more
of a sweet spot.

I was interested in this mostly because, using SuSE 7.0, it takes a Pentium/60
about four and a half minutes to get to n X logon from power-on.

- Jeff