Re: buildworld times

On Sat, 28 Feb 2004, Robert Watson wrote:

>
> On Sat, 28 Feb 2004, Vincent Poy wrote:
>
> > On Sat, 28 Feb 2004, Robert Watson wrote:
> >
> > > On Sat, 28 Feb 2004, Vincent Poy wrote:
> > >
> > > > > 2.5 hours seems a little high and would seem to indicate that you're
> > > > > building world under a kernel that has all the debugging options enabled.
> > > > > Could you make your kernel config available?
> > > >
> > > > 	Yeah, I recall that -CURRENT on a Mobile PII 366Mhz took the
> > > > same amount of time so I would imagine the P4 would be faster since I
> > > > remember PIII running at 800Mhz or so would take about 2 hours and the
> > > > Athlon K7 at 1.2Ghz was about a little over an hour.  I'm using the
> > > > standard GENERIC kernel and do have the debugging options enabled.
> > >
> > > Turning off the debugging options (especially WITNESS) can have a dramatic
> > > effect on performance.  Give it a spin.  :-)
> >
> > 	Besides the WITNESS and WITNESS_SKIPSPIN, do these have a big
> > effect as well?
> >
> > options         DDB
>
> No runtime cost, and useful if anything goes wrong :-).
>
> > options         INVARIANTS
>
> Small but non-zero cost.
>
> > options         INVARIANT_SUPPORT
>
> Space overhead, but other than memory overhead, no run-time cost.
>
> > makeoptions DEBUG=-g
>
> Makes your kernel build real slow, but won't change the kernel speed.
>
> As you point out, debugging problems is a lot easier if you run with
> INVARIANTS+WITNESS.  However, you may well see build times halve or more
> by running without WITNESS.

	I always thought INVARIANTS caused slow performance as well.
Ofcourse, it does seem all the stuff mentioned above is disabled in a
-RELEASE GENERIC kernel so that may be it as well.


Cheers,
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