Re: please revert bogus patch to vmscan.c

Victor Yodaiken
2001-10-30T17:56:26Z

On Tue, Oct 30, 2001 at 09:17:31AM -0800, Linus Torvalds wrote:
> I still have the occasional nightmares about the IBM block diagrams
> "explaining" the PowerPC MMU in their technical documentation.
>
> There's probably a perfectly valid explanation for them, though (*).
>
> Linus
>
> (*) Probably along the lines of the designers being so high on LSD that
> they thought it was a really cool idea. That would certainly explain it in
> a very logical fashion.

All the studies I saw were back from the days when
cache-speed/expensive-memory-speed was close to 1. In this case, the
effect of randomizing memory fetches is no big deal. The rest
of standard PPC mmu architecture is pretty nice, but, if the Alpha
architects could decide to use the PC cmos clock as their only
prgrammable timer, and the Itanium guys could decide to put in a single
shift-mask path, why shouldn't the IBM designers get to destroy cache
by wasting a bunch of CPU area logic?