Messages in this thread | | | Date | Wed, 30 May 2012 20:34:06 +0200 | From | Andrea Arcangeli <> | Subject | Re: [PATCH 04/35] autonuma: define _PAGE_NUMA_PTE and _PAGE_NUMA_PMD |
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Hi Konrad,
On Wed, May 30, 2012 at 02:22:49PM -0400, Konrad Rzeszutek Wilk wrote: > Thank you for loking at this from the xen side. The interesting thing > is that I believe the _PAGE_PAT (or _PAGE_PSE) is actually used on > Xen on PTEs. It is used to mark the pages WC. <sigh>
Oops, I'm using _PAGE_PSE too on the pte, but only when it's unmapped.
static inline int pte_numa(pte_t pte) { return (pte_flags(pte) & (_PAGE_NUMA_PTE|_PAGE_PRESENT)) == _PAGE_NUMA_PTE; }
And _PAGE_UNUSED2 (_PAGE_IOMAP) is used for the pmd but _PAGE_IOMAP by Xen should only be set on ptes.
The only way to use _PAGE_PSE safe on the pte is if the pte is non-present, is this what Xen is also doing? (in turn colliding with pte_numa)
Now if I shrink the size of the page_autonuma to one entry per pmd (instead of per pte) I may as well drop pte_numa entirely and only leave pmd_numa. At the moment it's possible to switch between the two models at runtime with sysctl (if one wants to do a more expensive granular tracking). I'm still uncertain on the best way to shrink the page_autonuma size we'll see.
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