During hugepage unmap, TLB flush is currently issued
at every PAGE_SIZE'd boundary which is unnecessary. We
now issue the flush at REAL_HPAGE_SIZE boundaries only.
Without this patch workloads which unmap a large hugepage
backed VMA region get CPU lockups due to excessive TLB
flush calls.
Signed-off-by: Nitin Gupta <nitin.m.gupta@xxxxxxxxxx>
---
arch/sparc/mm/hugetlbpage.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/arch/sparc/mm/hugetlbpage.c b/arch/sparc/mm/hugetlbpage.c
index 131eaf4..48927cb 100644
--- a/arch/sparc/mm/hugetlbpage.c
+++ b/arch/sparc/mm/hugetlbpage.c
@@ -193,16 +193,24 @@ pte_t huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
pte_t *ptep)
{
pte_t entry;
- int i;
+ int i, pte_count;
entry = *ptep;
if (pte_present(entry))
mm->context.huge_pte_count--;
addr &= HPAGE_MASK;
+ pte_count = 1 << HUGETLB_PAGE_ORDER;
- for (i = 0; i < (1 << HUGETLB_PAGE_ORDER); i++) {
- pte_clear(mm, addr, ptep);
+ /*
+ * pte_clear issues TLB flush which is required
+ * only for REAL_HPAGE_SIZE aligned addresses.
+ */
+ pte_clear(mm, addr, ptep);
+ pte_clear(mm, addr + REAL_HPAGE_SIZE, ptep + pte_count / 2);
+ ptep++;
+ for (i = 1; i < pte_count; i++) {
+ *ptep = __pte(0UL);
addr += PAGE_SIZE;
ptep++;
}
--
2.6.4
--
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