The patch titled
Subject: mm: numa: avoid unnecessary TLB flushes when setting NUMA hinting entries
has been added to the -mm tree. Its filename is
mm-numa-avoid-unnecessary-tlb-flushes-when-setting-numa-hinting-entries.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-numa-avoid-unnecessary-tlb-flushes-when-setting-numa-hinting-entries.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-numa-avoid-unnecessary-tlb-flushes-when-setting-numa-hinting-entries.patch
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------------------------------------------------------
From: Mel Gorman <mgorman@xxxxxxx>
Subject: 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@xxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Dave Jones <davej@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Kirill Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Sasha Levin <sasha.levin@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 14 ++++++++------
mm/mprotect.c | 4 ++++
2 files changed, 12 insertions(+), 6 deletions(-)
diff -puN mm/huge_memory.c~mm-numa-avoid-unnecessary-tlb-flushes-when-setting-numa-hinting-entries mm/huge_memory.c
--- a/mm/huge_memory.c~mm-numa-avoid-unnecessary-tlb-flushes-when-setting-numa-hinting-entries
+++ a/mm/huge_memory.c
@@ -1519,12 +1519,14 @@ int change_huge_pmd(struct vm_area_struc
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);
}
diff -puN mm/mprotect.c~mm-numa-avoid-unnecessary-tlb-flushes-when-setting-numa-hinting-entries mm/mprotect.c
--- a/mm/mprotect.c~mm-numa-avoid-unnecessary-tlb-flushes-when-setting-numa-hinting-entries
+++ a/mm/mprotect.c
@@ -86,6 +86,10 @@ static unsigned long change_pte_range(st
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);
_
Patches currently in -mm which might be from mgorman@xxxxxxx are
mm-debug-pagealloc-prepare-boottime-configurable-on-off.patch
mm-vmscan-prevent-kswapd-livelock-due-to-pfmemalloc-throttled-process-being-killed.patch
mm-page_alloc-place-zone_id-check-before-vm_bug_on_page-check.patch
mm-vmscan-wake-up-all-pfmemalloc-throttled-processes-at-once.patch
mm-numa-do-not-dereference-pmd-outside-of-the-lock-during-numa-hinting-fault.patch
mm-add-p-protnone-helpers-for-use-by-numa-balancing.patch
mm-convert-p_numa-users-to-p_protnone_numa.patch
ppc64-add-paranoid-warnings-for-unexpected-dsisr_protfault.patch
mm-convert-p_mknonnuma-and-remaining-page-table-manipulations.patch
mm-remove-remaining-references-to-numa-hinting-bits-and-helpers.patch
mm-numa-do-not-trap-faults-on-the-huge-zero-page.patch
x86-mm-restore-original-pte_special-check.patch
mm-numa-add-paranoid-check-around-pte_protnone_numa.patch
mm-numa-avoid-unnecessary-tlb-flushes-when-setting-numa-hinting-entries.patch
do_shared_fault-check-that-mmap_sem-is-held.patch
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