Re: make: dynamic scaling of maxJobs ?

[Alan Barrett <apb%cequrux.com@localhost>]

On Sat, 03 Aug 2013, Simon J. Gerraty wrote:
> Alan Barrett writes:
> > I sometimes use wrapper scripts that run make -j 
> > $(choose_maxjobs.sh).  Is it really worthwhile to add the 
> > complexity to make itself, instead of leaving it in a wrapper 
> > script?
>
> As I said, that's what we've been doing for many years.  It 
> works great for a machine dedicated to a single build.
>
> But it cannot not work well when N developers are sharing a box 
> with M cores.

I have just re-read your message and I see I missed this important 
part:

> > and make will run that to get an initial value, and re-run it 
> > occasionally to adjust.

while I did not miss this part:

> > This only applies to the initial instance of make, the 
> > sub-makes get a normal -j value

so, I thought that only the top-level make would run the script, 
and that it would run it only once, giving behaviour identical to 
making the choice in a wrapper script.

I now see my mistake, and agree that your suggestion is useful.

--apb (Alan Barrett)