Re: 2.4.15pre6aa1 (fixes google VM problem)

[Linus Torvalds]

On Mon, 19 Nov 2001, Linus Torvalds wrote:
>
> So why not have the much simpler patch to just say:
>
> 	min = 0;
> 	for (;;) {
> 		zone_t *z = *(zone++);
> 		..
> 		min = (min >> 2) + z->pages_low;
> 		..

Actually, as we already limit "pages_low" (for _all_ zones) through the
use of zone_balance_max[], I don't think we need to even age the minimum
pages.

And instead of doing "zone->free_pages - (1UL << order)" in
zone_free_pages(), we can do it much more efficiently just once for the
for-loop by initializing "min" to "(1UL << order)" instead of zero. So
we'd just make the loop be

	min = (1UL << order);
	for (;;) {
		zone_t *z = *(zone++);
		..
		min += z->pages_low;
		...

instead, which is even simpler (and then just compare page->free_pages
against "min" directly..

		Linus