Re: 2.5.53-mm2

[William Lee Irwin III <wli@holomorphy.com>]

On Sat, Dec 28, 2002 at 04:52:20PM -0800, Andrew Morton wrote:
>> wli-11_pgd_ctor.patch

On Wed, Jan 01, 2003 at 08:53:27PM -0800, William Lee Irwin III wrote:
> A moment's reflection on the subject suggests to me it's worthwhile to
> generalize pgd_ctor support so it works (without #ifdefs!) on both PAE
> and non-PAE. This tiny tweak is actually more noticeably beneficial
> on non-PAE systems but only really because pgd_alloc() is more visible;
> the most likely reason it's less visible on PAE is "other overhead".
> It looks particularly nice since it removes more code than it adds.
> Touch tested on NUMA-Q (PAE). OFTC #kn testers testing the non-PAE case.

For those needing more interpretation, this is essentially a reinstatement
of the 2.4.x-style pgd/pmd cache optimization in a leak-free and accounted
(in /proc/slabinfo) manner.

The point of the optimizations is that these initializations are large
cache hits to take in a single shot, and in the PAE case, amount to a
full L1 cache flush as they traverse almost an entire 16K.

No rigorous benchmarking has been done yet.

Bill
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