Messages in this thread | | | Subject | Re: Note describing poor dcache utilization under high memory pressure | From | Momchil Velikov <> | Date | 29 Jan 2002 12:18:42 +0200 |
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>>>>> "William" == William Lee Irwin <wli@holomorphy.com> writes:
William> On Tue, Jan 29, 2002 at 09:55:02AM +0100, Daniel Phillips wrote: >> It's only touching the ptes on tables that are actually used, so if a parent >> with a massive amount of mapped memory forks a child that only instantiates >> a small portion of it (common situation) then the saving is pretty big.
William> Please correct my attempt at clarifying this: William> The COW markings are done at the next higher level of hierarchy above William> the pte's themselves, and so experience the radix tree branch factor William> reduction in the amount of work done at fork-time in comparison to a William> full pagetable copy on fork.
COW at pgd/pmd level is ia32-ism, unlike COW at pte level.
Regards, -velco
PS. Well, the whole pgd/pmd/ptb stuff is ia32-ism, but that's another story.
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