[PATCH v6 03/20] powerpc/mm: Avoid useless lock with single page fragments
From: Christophe Leroy <hidden>
Date: 2018-10-19 06:55:02
Also in:
lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
There is no point in taking the page table lock as pte_frag or pmd_frag are always NULL when we have only one fragment. Reviewed-by: Aneesh Kumar K.V <redacted> Signed-off-by: Christophe Leroy <redacted> --- arch/powerpc/mm/pgtable-book3s64.c | 3 +++ arch/powerpc/mm/pgtable-frag.c | 3 +++ 2 files changed, 6 insertions(+)
diff --git a/arch/powerpc/mm/pgtable-book3s64.c b/arch/powerpc/mm/pgtable-book3s64.c
index 84ff3403239c..9f78db7c8c2a 100644
--- a/arch/powerpc/mm/pgtable-book3s64.c
+++ b/arch/powerpc/mm/pgtable-book3s64.c@@ -243,6 +243,9 @@ static pmd_t *get_pmd_from_cache(struct mm_struct *mm) { void *pmd_frag, *ret; + if (PMD_FRAG_NR == 1) + return NULL; + spin_lock(&mm->page_table_lock); ret = mm->context.pmd_frag; if (ret) {
diff --git a/arch/powerpc/mm/pgtable-frag.c b/arch/powerpc/mm/pgtable-frag.c
index d61e7c2a9a79..7544d0d7177d 100644
--- a/arch/powerpc/mm/pgtable-frag.c
+++ b/arch/powerpc/mm/pgtable-frag.c@@ -34,6 +34,9 @@ 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) {
--
2.13.3