buildworld times

[Scott Long]

On Wed, 3 Mar 2004, Stefan [iso-8859-1] E=DFer wrote:
>
> I do not understand, why 'ratio' comes out that different (92-103% vs. 13=
7-148%)
> for 5.2.1 vs. -CURRENT (for -j4 and up, where HT plays a role).
>
> Is the process accounting different, or has the scheduler been changed to=
 make
> better use of logical processors ???

ULE is better in 5.2-CURRENT than in RELENG_5_2.  However, the significant
change that is contributing to this is the improvements to make(1).  Prior
to 5.2-CURRENT, 'make -jX' would poll every 20ms for completed children,
and then schedule new children.  Now there is a simplistic SIGCHILD handler
that allows new children to be scheduled immediately, and of course
eliminates the overhead of the polling.  Since buildworld is such a large
consumer of fork/exec, it's not surprising that this change helps a lot.

Scott