Thread (25 messages) 25 messages, 2 authors, 2018-09-25

Re: [PATCH v4 15/20] powerpc/mm: Avoid useless lock with single page fragments

From: Aneesh Kumar K.V <hidden>
Date: 2018-09-19 03:35:30
Also in: lkml

On 9/18/18 10:27 PM, Christophe Leroy wrote:
quoted hunk ↗ jump to hunk
There is no point in taking the page table lock as
pte_frag is always NULL when we have only one fragment.

Signed-off-by: Christophe Leroy <redacted>
---
  arch/powerpc/mm/pgtable-frag.c | 3 +++
  1 file changed, 3 insertions(+)
diff --git a/arch/powerpc/mm/pgtable-frag.c b/arch/powerpc/mm/pgtable-frag.c
index bc924822dcd6..ab4910e92aaf 100644
--- a/arch/powerpc/mm/pgtable-frag.c
+++ b/arch/powerpc/mm/pgtable-frag.c
@@ -85,6 +85,9 @@ static pte_t *get_pte_from_cache(struct mm_struct *mm)
  {
  	void *pte_frag, *ret;

+	if (PTE_FRAG_NR == 1)
+		return NULL;
+
  	spin_lock(&mm->page_table_lock);
  	ret = mm->context.pte_frag;
  	if (ret) {
May be update get_pmd_from_cache too?

-aneesh
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