Re: [PATCH v10 4/4] arm64: support batched/deferred tlb shootdown during page reclamation/migration

Catalin Marinas
2023-07-16T15:12:03Z

On Mon, Jul 10, 2023 at 04:39:14PM +0800, Yicong Yang wrote:
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 7856c3a3e35a..f0ce8208c57f 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -96,6 +96,7 @@ config ARM64
> select ARCH_SUPPORTS_NUMA_BALANCING
> select ARCH_SUPPORTS_PAGE_TABLE_CHECK
> select ARCH_SUPPORTS_PER_VMA_LOCK
> + select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH if EXPERT

I don't want EXPERT to turn on a feature that's not selectable by the
user. This would lead to different performance behaviour based on
EXPERT. Just select it unconditionally.

> diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
> index 412a3b9a3c25..4bb9cec62e26 100644
> --- a/arch/arm64/include/asm/tlbflush.h
> +++ b/arch/arm64/include/asm/tlbflush.h
> @@ -254,17 +254,23 @@ static inline void flush_tlb_mm(struct mm_struct *mm)
> dsb(ish);
> }
>
> -static inline void flush_tlb_page_nosync(struct vm_area_struct *vma,
> - unsigned long uaddr)
> +static inline void __flush_tlb_page_nosync(struct mm_struct *mm,
> + unsigned long uaddr)
> {
> unsigned long addr;
>
> dsb(ishst);
> - addr = __TLBI_VADDR(uaddr, ASID(vma->vm_mm));
> + addr = __TLBI_VADDR(uaddr, ASID(mm));
> __tlbi(vale1is, addr);
> __tlbi_user(vale1is, addr);
> }
>
> +static inline void flush_tlb_page_nosync(struct vm_area_struct *vma,
> + unsigned long uaddr)
> +{
> + return __flush_tlb_page_nosync(vma->vm_mm, uaddr);
> +}
> +
> static inline void flush_tlb_page(struct vm_area_struct *vma,
> unsigned long uaddr)
> {
> @@ -272,6 +278,42 @@ static inline void flush_tlb_page(struct vm_area_struct *vma,
> dsb(ish);
> }
>
> +#ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH

If it's selected unconditionally, we won't need this #ifdef here.

> +
> +static inline bool arch_tlbbatch_should_defer(struct mm_struct *mm)
> +{
> +#ifdef CONFIG_ARM64_WORKAROUND_REPEAT_TLBI
> + /*
> + * TLB flush deferral is not required on systems, which are affected with

"affected by" and drop the comma before "which".

--
Catalin