Re: [RFC] Convert pgtable cache to slab

David Mosberger
2004-10-14T07:44:59Z

>>>>> On Wed, 13 Oct 2004 11:59:56 -0700, William Lee Irwin III <wli@holomorphy.com> said:

William> On Wed, Oct 13, 2004 at 02:47:43PM -0400, Martin
William> K. Petersen wrote:
>> This patch makes the page table cache on IA-64 use the slab
>> instead of standard page allocations. It's based upon Bill
>> Irwin's code for ppc64. With this patch I got a significant
>> improvement in page fault time. Standard 2.4.x was about 700ns
>> on average. Generic 2.6.9rc4 is 3-4 usec, whereas the slabified
>> pgtcache drops us back down to 600-700 ns. Tested on zx1 and
>> sn2. The biggest caveat is that I've had to postpone setting up
>> the gate page until the pgt slab has been initialized. That
>> wasn't an issue with the existing page-based allocation scheme.
>> David - how do you prefer I handle this?

William> Nice! I got reports that it would not be beneficial when I
William> thought about going over this earlier. I suppose it's a
William> small vindication of my methods to see the original
William> objection contradicted here. =)

What was the original comment relative to? 2.4 or 2.6? In 2.6 we
lost the PTE quick-list, which I think is where the big overhead came
from. Right, Martin?

--david