Gentle reminder for review comments.
Also adding Naoya to CC whom I forgot last time, sorry.
Thanks,
Nitin
On 02/03/2016 03:00 PM, Nitin Gupta wrote:
> During hugepage unmap, TSB and TLB flushes are currently
> issued at every PAGE_SIZE'd boundary which is unnecessary.
> We now issue the flush at REAL_HPAGE_SIZE boundaries only.
>
> Without this patch workloads which unmap a large hugepage
> backed VMA region get CPU lockups due to excessive TLB
> flush calls.
>
> Signed-off-by: Nitin Gupta <nitin.m.gupta@xxxxxxxxxx>
> ---
> arch/sparc/include/asm/tlbflush_64.h | 3 ++-
> arch/sparc/mm/hugetlbpage.c | 7 ++++++-
> arch/sparc/mm/tlb.c | 2 +-
> arch/sparc/mm/tsb.c | 21 ++++++++++++++-------
> 4 files changed, 23 insertions(+), 10 deletions(-)
>
> Changelog v1 vs v2:
> - Access PTEs in order (David Miller)
> - Issue TLB and TSB flush after clearing PTEs (David Miller)
>
> diff --git a/arch/sparc/include/asm/tlbflush_64.h b/arch/sparc/include/asm/tlbflush_64.h
> index dea1cfa..5c28f78 100644
> --- a/arch/sparc/include/asm/tlbflush_64.h
> +++ b/arch/sparc/include/asm/tlbflush_64.h
> @@ -16,7 +16,8 @@ struct tlb_batch {
>
> void flush_tsb_kernel_range(unsigned long start, unsigned long end);
> void flush_tsb_user(struct tlb_batch *tb);
> -void flush_tsb_user_page(struct mm_struct *mm, unsigned long vaddr);
> +void flush_tsb_user_page(struct mm_struct *mm, unsigned long vaddr,
> + bool is_huge);
>
> /* TLB flush operations. */
>
> diff --git a/arch/sparc/mm/hugetlbpage.c b/arch/sparc/mm/hugetlbpage.c
> index 131eaf4..d8f625c 100644
> --- a/arch/sparc/mm/hugetlbpage.c
> +++ b/arch/sparc/mm/hugetlbpage.c
> @@ -202,10 +202,15 @@ pte_t huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
> addr &= HPAGE_MASK;
>
> for (i = 0; i < (1 << HUGETLB_PAGE_ORDER); i++) {
> - pte_clear(mm, addr, ptep);
> + *ptep = __pte(0UL);
> addr += PAGE_SIZE;
> ptep++;
> }
> + /* Issue TSB and TLB flush at REAL_HPAGE_SIZE boundaries */
> + flush_tsb_user_page(mm, addr, true);
> + flush_tsb_user_page(mm, addr + REAL_HPAGE_SIZE, true);
> + global_flush_tlb_page(mm, addr);
> + global_flush_tlb_page(mm, addr + REAL_HPAGE_SIZE);
>
> return entry;
> }
> diff --git a/arch/sparc/mm/tlb.c b/arch/sparc/mm/tlb.c
> index 9df2190..1a5de57 100644
> --- a/arch/sparc/mm/tlb.c
> +++ b/arch/sparc/mm/tlb.c
> @@ -84,7 +84,7 @@ static void tlb_batch_add_one(struct mm_struct *mm, unsigned long vaddr,
> }
>
> if (!tb->active) {
> - flush_tsb_user_page(mm, vaddr);
> + flush_tsb_user_page(mm, vaddr, false);
> global_flush_tlb_page(mm, vaddr);
> goto out;
> }
> diff --git a/arch/sparc/mm/tsb.c b/arch/sparc/mm/tsb.c
> index a065766..3af2848 100644
> --- a/arch/sparc/mm/tsb.c
> +++ b/arch/sparc/mm/tsb.c
> @@ -94,18 +94,25 @@ void flush_tsb_user(struct tlb_batch *tb)
> spin_unlock_irqrestore(&mm->context.lock, flags);
> }
>
> -void flush_tsb_user_page(struct mm_struct *mm, unsigned long vaddr)
> +/*
> + * @is_huge is true if the page containing @vaddr is guaranteed to
> + * be a huge page. If false, then TSBs for both, base and huge page
> + * size are flushed.
> + */
> +void flush_tsb_user_page(struct mm_struct *mm, unsigned long vaddr,
> + bool is_huge)
> {
> unsigned long nentries, base, flags;
>
> spin_lock_irqsave(&mm->context.lock, flags);
>
> - base = (unsigned long) mm->context.tsb_block[MM_TSB_BASE].tsb;
> - nentries = mm->context.tsb_block[MM_TSB_BASE].tsb_nentries;
> - if (tlb_type == cheetah_plus || tlb_type == hypervisor)
> - base = __pa(base);
> - __flush_tsb_one_entry(base, vaddr, PAGE_SHIFT, nentries);
> -
> + if (!is_huge) {
> + base = (unsigned long) mm->context.tsb_block[MM_TSB_BASE].tsb;
> + nentries = mm->context.tsb_block[MM_TSB_BASE].tsb_nentries;
> + if (tlb_type == cheetah_plus || tlb_type == hypervisor)
> + base = __pa(base);
> + __flush_tsb_one_entry(base, vaddr, PAGE_SHIFT, nentries);
> + }
> #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
> if (mm->context.tsb_block[MM_TSB_HUGE].tsb) {
> base = (unsigned long) mm->context.tsb_block[MM_TSB_HUGE].tsb;
>
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