Re: Fwd: [RFC]serialize the output of parallel make?

[Howard Chu]

Edward Welbourne wrote:
> > 2x is too much. 1.5x has been the best in my experience, any more than that
> > and you're losing too much CPU to scheduling overhead instead of real work.
> > Any less and you're giving up too much in idle or I/O time.
>
> This depends a bit on whether you're using icecc or some similar
> distributed compilation system.  I believe a better approach is to set
> a generous -j, such as twice the count of CPUs, but impose a load
> limit using -l, tuned rather more carefully.  Scheduling overhead
> contributes to load, so is taken into account this way.

Perhaps in a perfect world -l would be useful. In fact, since load averages 
are calculated so slowly, by the time your -l limit is reached the actual CPU 
load will have blown past it and your machine will be thrashing. That's the 
entire reason I came up with the -j implementation in the first place.

--
  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/