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mm: numa: avoid unnecessary TLB flushes when setting NUMA hinting entries

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If a PTE or PMD is already marked NUMA when scanning to mark entries for
NUMA hinting then it is not necessary to update the entry and incur a TLB
flush penalty.  Avoid the avoidhead where possible.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mel Gorman 2015-02-12 14:58:44 -08:00 • committed by Linus Torvalds
commit 10c1045f28
2 changed files with 12 additions and 6 deletions
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14
mm/huge_memory.c
View file

@ -1493,12 +1493,14 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
return 0;
}
ret = 1;
entry = pmdp_get_and_clear_notify(mm, addr, pmd);
entry = pmd_modify(entry, newprot);
ret = HPAGE_PMD_NR;
set_pmd_at(mm, addr, pmd, entry);
BUG_ON(pmd_write(entry));
if (!prot_numa || !pmd_protnone(*pmd)) {
ret = 1;
entry = pmdp_get_and_clear_notify(mm, addr, pmd);
entry = pmd_modify(entry, newprot);
ret = HPAGE_PMD_NR;
set_pmd_at(mm, addr, pmd, entry);
BUG_ON(pmd_write(entry));
}
spin_unlock(ptl);
}

4
mm/mprotect.c
View file

@ -86,6 +86,10 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
page = vm_normal_page(vma, addr, oldpte);
if (!page || PageKsm(page))
continue;
/* Avoid TLB flush if possible */
if (pte_protnone(oldpte))
continue;
}
ptent = ptep_modify_prot_start(mm, addr, pte);