Clarification needed on Handbook: Tracking for Multiple Machines
tfrank at optushome.com.au
Mon Feb 23 16:49:40 PST 2004
On Mon, Feb 23, 2004 at 10:46:07AM -0600, D J Hawkey Jr wrote:
> On Feb 23, at 09:12 AM, M. Warner Losh wrote:
> > In message: <20040222172039.GA25979 at sheol.localdomain>
> > D J Hawkey Jr <hawkeyd at visi.com> writes:
> > : True or False: Setting CPUTYPE to the lowest target CPU ("p2") in
> > : a build machine's make.conf will cripple the performance of target
> > : machines with higher CPUs ("p3", "p4", "i586", "i686", etc.).
> > False. It might have a minor impact on performance, but not a major
> > one. At least in my experience. Minor here means < 10% for something
> > like the world stone. Cripple to me implies > 25%.
> OK, thanks. Just to satisfy my anal-retentive side, would that ~10%
> degradation be a higher level of performance on a PIII (or higher)
> with no CPUTYPE specified at all, given the same *FLAGS?
Perhaps the easiest option is to actually try it and see what the results
> > : If "True", for optimized code across all machines, the code should
> > : just be built on each machine, right?
> > That would give slightly better performance. However, it can be more
> > pain than it is worth if the number of machine types is high.
> Consuming considerably more time and disk space, a shell script to
> alter make.conf and rename /usr/obj between the build for each machine
> is doable, though pro'lly not worth it. The install at each each box
> would just have to mount it's corresponding /usr/obj tree.
Just need to set __MAKE_CONF and MAKEOBJDIRPREFIX before running the build.
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