iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

powerpc/64s: Implement ptep_clear_flush_young that does not flush TLBs

Browse Source 
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
This commit is contained in:
Nicholas Piggin 2020-12-17 23:47:31 +10:00 committed by Michael Ellerman
parent 032b7f0893
commit 3cb1aa7aa3
1 changed files with 20 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
arch/powerpc/include/asm/book3s/64/pgtable.h
View File

@ -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));