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

[Yicong Yang]

On 2023/7/16 23:11, Catalin Marinas wrote:
> 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.

Got it. will drop it and address the comment below.

Thanks.

> 
>> 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".
>