[nycbug-talk] make -jN performance

Pete Wright pete
Wed Jan 19 17:34:58 EST 2005

On Wed, Jan 19, 2005 at 03:24:17PM -0600, Tillman Hodgson wrote:
> On Tue, Jan 18, 2005 at 05:59:15PM -0500, Pete Wright wrote:
> > Hey bob all,
> > 	so instead of relying on blind faith I ran some tests to see the truth
> > in the make -jN statements in the FreeBSD handbook.  While I agree with what 
> > bob stated regarding the "-j" flag I thought that maybe there was something in
> > the makeworld process that got around these issues.  Well I hacked up a small
> > shell script to test this out and the findings were not what I expected (and 
> > frankly not what I remember experiencing in the past).  The make times flattened
> > out after make -j2 buildworld on an SMP system running 5.3.  I've posted a pretty detailed
> > post to freebsd-stable@ and hope to get some feedback.  I'll keep you all posted
> > here as well if you all are interested.
> About a year ago I did some tests as well.
> http://lists.freebsd.org/pipermail/freebsd-questions/2004-January/032105.html
> I posted this to the FreeBSD questions mailing list though it didn't
> generate much discussion. After testing for myself and seeing these
> results, I quit using -j# with make on single CPU boxes.
> Combined with your results, it looks like one job per CPU is the best
> that the build infrastructure can do.

hmm...then it looks like I should submit a PR to the doc team then...well 
atleast it was an interesting exercise :)


Peter Wright
pete at nomadlogic.org

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