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| author | Nicholas Piggin <npiggin@gmail.com> | 2020-05-04 15:29:07 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2020-05-28 16:24:34 +0300 |
| commit | 18594f9b8c45484bd527ebc6b08383b95f58ba73 (patch) | |
| tree | f99e1b502708fb802af5b7b494216a68864a435e /arch/powerpc/mm/book3s64/hash_utils.c | |
| parent | e4f4ffa8a98c24a4ab482669b1e2b4cfce3f52f4 (diff) | |
| download | linux-18594f9b8c45484bd527ebc6b08383b95f58ba73.tar.xz | |
powerpc/64s/radix: Don't prefetch DAR in update_mmu_cache
The idea behind this prefetch was to kick off a page table walk before
returning from the fault, getting some pipelining advantage.
But this never showed up any noticable performance advantage, and in
fact with KUAP the prefetches are actually blocked and cause some
kind of micro-architectural fault. Removing this improves page fault
microbenchmark performance by about 9%.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Keep the early return in update_mmu_cache()]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200504122907.49304-1-npiggin@gmail.com
Diffstat (limited to 'arch/powerpc/mm/book3s64/hash_utils.c')
| -rw-r--r-- | arch/powerpc/mm/book3s64/hash_utils.c | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c index 622c6e8e9fa6..0124003e60d0 100644 --- a/arch/powerpc/mm/book3s64/hash_utils.c +++ b/arch/powerpc/mm/book3s64/hash_utils.c @@ -1634,10 +1634,8 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long address, unsigned long trap; bool is_exec; - if (radix_enabled()) { - prefetch((void *)address); + if (radix_enabled()) return; - } /* We only want HPTEs for linux PTEs that have _PAGE_ACCESSED set */ if (!pte_young(*ptep) || address >= TASK_SIZE) |