On 07/12/2012 02:50 PM, Andrea Arcangeli wrote:
On Mon, Jul 02, 2012 at 12:24:36AM -0400, Rik van Riel wrote:
On 06/28/2012 08:56 AM, Andrea Arcangeli wrote:
If any of the ptes that khugepaged is collapsing was a pte_numa, the
resulting trans huge pmd will be a pmd_numa too.
Why?
If some of the ptes already got faulted in and made really
resident again, why do you want to incur a new NUMA fault
on the newly collapsed hugepage?
If we don't set pmd_numa on the collapsed hugepage, the result is that
we'll understimate the thread NUMA affinity to the node where the
hugepage is located (mm affinity is recorded independently by the NUMA
hinting page faults).
If it's better or worse I guess depends on luck, we just lose
information.
Fair enough.
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