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SubjectRe: [PATCH 17/50] mm: Do not flush TLB during protection change if !pte_present && !migration_entry
On Tue, Sep 10, 2013 at 10:31:57AM +0100, Mel Gorman wrote:
> NUMA PTE scanning is expensive both in terms of the scanning itself and
> the TLB flush if there are any updates. Currently non-present PTEs are
> accounted for as an update and incurring a TLB flush where it is only
> necessary for anonymous migration entries. This patch addresses the
> problem and should reduce TLB flushes.
>
> Signed-off-by: Mel Gorman <mgorman@suse.de>
> ---
> mm/mprotect.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/mm/mprotect.c b/mm/mprotect.c
> index 1f9b54b..1e9cef0 100644
> --- a/mm/mprotect.c
> +++ b/mm/mprotect.c
> @@ -109,8 +109,9 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
> make_migration_entry_read(&entry);
> set_pte_at(mm, addr, pte,
> swp_entry_to_pte(entry));
> +
> + pages++;
> }
> - pages++;
> }
> } while (pte++, addr += PAGE_SIZE, addr != end);
> arch_leave_lazy_mmu_mode();

Should we fold this into patch 7 ?


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