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authorMel Gorman <mgorman@suse.de>2015-02-12 14:58:44 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-02-12 18:54:08 -0800
commit10c1045f28e86ac90589a188f0be2d7a4347efdf (patch)
tree1bb321876125ca1afb061ada97462fb6bb23fc2c /mm/huge_memory.c
parentc0e7cad9f2390087b53e26e7b98958d8793ee02d (diff)
downloadlwn-10c1045f28e86ac90589a188f0be2d7a4347efdf.tar.gz
lwn-10c1045f28e86ac90589a188f0be2d7a4347efdf.zip
mm: numa: avoid unnecessary TLB flushes when setting NUMA hinting entries
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>
Diffstat (limited to 'mm/huge_memory.c')
-rw-r--r--mm/huge_memory.c14
1 files changed, 8 insertions, 6 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 8e07342b52c0..fc00c8cb5a82 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -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);
}