diff options
| author | Nicholas Piggin <npiggin@gmail.com> | 2020-12-17 23:47:31 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2021-02-09 01:09:45 +1100 |
| commit | 3cb1aa7aa39402f4f2cb847b1f16ade3bce43a97 (patch) | |
| tree | e080be0f37477a4b24d7e0a836fc4a27117b40e2 /arch/powerpc/include | |
| parent | 032b7f08932c9b212952d6d585e45b2941b3e8be (diff) | |
powerpc/64s: Implement ptep_clear_flush_young that does not flush TLBs
Similarly to the x86 commit b13b1d2d8692 ("x86/mm: In the PTE swapout
page reclaim case clear the accessed bit instead of flushing the TLB"),
implement ptep_clear_flush_young that does not actually flush the TLB
in the case the referenced bit is cleared.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201217134731.488135-8-npiggin@gmail.com
Diffstat (limited to 'arch/powerpc/include')
| -rw-r--r-- | arch/powerpc/include/asm/book3s/64/pgtable.h | 23 |
1 files changed, 20 insertions, 3 deletions
diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h index a39886681629..058601efbc8a 100644 --- a/arch/powerpc/include/asm/book3s/64/pgtable.h +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h @@ -388,11 +388,28 @@ static inline int __ptep_test_and_clear_young(struct mm_struct *mm, #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG #define ptep_test_and_clear_young(__vma, __addr, __ptep) \ ({ \ - int __r; \ - __r = __ptep_test_and_clear_young((__vma)->vm_mm, __addr, __ptep); \ - __r; \ + __ptep_test_and_clear_young((__vma)->vm_mm, __addr, __ptep); \ }) +/* + * On Book3S CPUs, clearing the accessed bit without a TLB flush + * doesn't cause data corruption. [ It could cause incorrect + * page aging and the (mistaken) reclaim of hot pages, but the + * chance of that should be relatively low. ] + * + * So as a performance optimization don't flush the TLB when + * clearing the accessed bit, it will eventually be flushed by + * a context switch or a VM operation anyway. [ In the rare + * event of it not getting flushed for a long time the delay + * shouldn't really matter because there's no real memory + * pressure for swapout to react to. ] + */ +#define __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH +#define ptep_clear_flush_young ptep_test_and_clear_young + +#define __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH +#define pmdp_clear_flush_young pmdp_test_and_clear_young + static inline int __pte_write(pte_t pte) { return !!(pte_raw(pte) & cpu_to_be64(_PAGE_WRITE)); |