Re: How do parallel builds scale?

[Bob Friesenhahn]

On Mon, 7 Mar 2011, Ralf Wildenhues wrote:
> > FWIW I think the cumulative plots make sense when trying to answer the
> > question “how many packages have a speedup <= X”.
>
> Well, if I'd ask a cumulative question I'd probably rather ask how many
> packages have a speedup >= X.  Small but significant difference.

Also, the nature of the packages.  For example 
recursive/non-recursive.  Total number of source lines (e.g. from 
'sloccount'). Number of objects built per Makefile.  Number of 
Makefiles.  Number of libraries linked.  Size (as from 'size' program) 
of final executable files.

> Can you please make your hardware specs available?  I've had two 16-way
> systems, and one could barely get more than a speedup of 2, while the
> other cucked away nicely at 10 or so.

Due to overlapping I/O, it is quite possible for builds to be 
super-linear.  At least that is what I typically see here.

Bob
--
Bob Friesenhahn
address@hidden, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/