Re: [Lhms-devel] [PATCH 0/7] Fragmentation Avoidance V19

Martin J. Bligh
2005-11-03T22:40:30Z

--On Thursday, November 03, 2005 11:35:28 -0800 Linus Torvalds <torvalds@osdl.org> wrote:

>
>
> On Thu, 3 Nov 2005, Martin J. Bligh wrote:
>>
>> Possibly, I can redo the calculations easily enough (have to go for now,
>> but I just sent the other ones). But we don't keep a fixed percentage of
>> memory free - we cap it ... perhaps we should though?
>
> I suspect the capping may well be from some old HIGHMEM interaction on x86
> (ie "don't keep half a gig free in the normal zone just because we have
> 16GB in the high-zone". We used to have serious balancing issues, and I
> wouldn't be surprised at all if there are remnants from that. Stuff that
> simply hasn't been visible, because not a lot of people had many many GB
> of memory even on machines that didn't need HIGHMEM.

But pages_min is based on the zone size, not the system size. And we
still cap it. Maybe that's just a mistake?

M.