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| author | Will Deacon <will@kernel.org> | 2020-11-24 18:49:26 +0000 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2021-01-20 14:46:04 +0000 |
| commit | 0388f9c7433024ccf3909b3404a745100f006a17 (patch) | |
| tree | 0d74c4b9b4829c052f466183d05fb02eca833c14 /arch/arm64/include/asm | |
| parent | 46bdb4277f98e70d0c91f4289897ade533fe9e80 (diff) | |
| download | lwn-0388f9c7433024ccf3909b3404a745100f006a17.tar.gz lwn-0388f9c7433024ccf3909b3404a745100f006a17.zip | |
arm64: mm: Implement arch_wants_old_prefaulted_pte()
On CPUs with hardware AF/DBM, initialising prefaulted PTEs as 'old'
improves vmscan behaviour and does not appear to introduce any overhead
elsewhere.
Implement arch_wants_old_prefaulted_pte() to return 'true' if we detect
hardware access flag support at runtime. This can be extended in future
based on MIDR matching if necessary.
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/include/asm')
| -rw-r--r-- | arch/arm64/include/asm/pgtable.h | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 501562793ce2..e17b96d0e4b5 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -980,7 +980,17 @@ static inline bool arch_faults_on_old_pte(void) return !cpu_has_hw_af(); } -#define arch_faults_on_old_pte arch_faults_on_old_pte +#define arch_faults_on_old_pte arch_faults_on_old_pte + +/* + * Experimentally, it's cheap to set the access flag in hardware and we + * benefit from prefaulting mappings as 'old' to start with. + */ +static inline bool arch_wants_old_prefaulted_pte(void) +{ + return !arch_faults_on_old_pte(); +} +#define arch_wants_old_prefaulted_pte arch_wants_old_prefaulted_pte #endif /* !__ASSEMBLY__ */ |