Re: [PATCH v6 1/2] mm/tlbbatch: Introduce arch_tlbbatch_should_defer()

haoxin
2022-11-15T06:46:01Z

在 2022/11/15 上午11:14, Yicong Yang 写道:
> From: Anshuman Khandual <khandual@linux.vnet.ibm.com>
>
> The entire scheme of deferred TLB flush in reclaim path rests on the
> fact that the cost to refill TLB entries is less than flushing out
> individual entries by sending IPI to remote CPUs. But architecture
> can have different ways to evaluate that. Hence apart from checking
> TTU_BATCH_FLUSH in the TTU flags, rest of the decision should be
> architecture specific.
>
> Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
> [https://lore.kernel.org/linuxppc-dev/20171101101735.2318-2-khandual@linux.vnet.ibm.com/]
> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
> [Rebase and fix incorrect return value type]
> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
> Reviewed-by: Barry Song <baohua@kernel.org>
> Tested-by: Punit Agrawal <punit.agrawal@bytedance.com>
> ---
> arch/x86/include/asm/tlbflush.h | 12 ++++++++++++
> mm/rmap.c | 9 +--------
> 2 files changed, 13 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
> index cda3118f3b27..8a497d902c16 100644
> --- a/arch/x86/include/asm/tlbflush.h
> +++ b/arch/x86/include/asm/tlbflush.h
> @@ -240,6 +240,18 @@ static inline void flush_tlb_page(struct vm_area_struct *vma, unsigned long a)
> flush_tlb_mm_range(vma->vm_mm, a, a + PAGE_SIZE, PAGE_SHIFT, false);
> }
>
> +static inline bool arch_tlbbatch_should_defer(struct mm_struct *mm)
> +{
> + bool should_defer = false;
> +
> + /* If remote CPUs need to be flushed then defer batch the flush */
> + if (cpumask_any_but(mm_cpumask(mm), get_cpu()) < nr_cpu_ids)
> + should_defer = true;
> + put_cpu();
> +
> + return should_defer;
> +}
> +
> static inline u64 inc_mm_tlb_gen(struct mm_struct *mm)
> {
> /*
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 2ec925e5fa6a..a9ab10bc0144 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -685,17 +685,10 @@ static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable)
> */
> static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags)
> {
> - bool should_defer = false;
> -
> if (!(flags & TTU_BATCH_FLUSH))
> return false;
>
> - /* If remote CPUs need to be flushed then defer batch the flush */
> - if (cpumask_any_but(mm_cpumask(mm), get_cpu()) < nr_cpu_ids)
> - should_defer = true;
> - put_cpu();
> -
> - return should_defer;
> + return arch_tlbbatch_should_defer(mm);
> }
>
LGTM, thanks

Reviewed-by: Xin Hao <xhao@linux.alibaba.com>
> /*