Jason R Thorpe <thorpej@zembu.com> writes:

> On Thu, Nov 30, 2000 at 04:59:40PM -0500, Laine Stump wrote:
> 
>  > I just updated to -current (from something around 1.5_BETA), built a
>  > kernel (after removing the existing build directory), rebooted, did
>  > make build of userland, rebooted again, then did another kernel
>  > build. I only noticed a difference of about 30 seconds 14:53 vs 15:23)
>  > between the first kernel build (done using 1.5_BETA) and the last one
>  > (using all 1.5L). Did I miss some change that I was supposed to make
>  > to enable UBC, or is this just not a good benchmark? (I'm using a more
>  > or less GENERIC kernel, btw, no setting of BUFPAGES, NBUFS or any of
>  > that)
> 
> Well, the reboot obviously cleared the cache that held all those
> source files....

I was figuring that eliminating the reread of all the .h files would
show an improvement.

> Try this:
> 
> 	Time kernel build
> 	reboot
> 	cd /usr/src/sys; find . -name "*.[chSs]" -exec cat {} \; > /dev/null
> 	Time kernel build

No change. Looks like a kernel build either doesn't reuse enough files
quickly enough to make a difference, or 128MB of RAM is small enough
that things get discarded from the cache before they're reread.

Anyway, I'll just take everyone's word that there's nothing special I
need to do to turn on UBC.