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SubjectRe: [PATCH 1/2] mm: add per-order mTHP split counters
On Wed, Apr 24, 2024 at 6:53 AM Lance Yang <ioworker0@gmail.com> wrote:
>
> At present, the split counters in THP statistics no longer include
> PTE-mapped mTHP. Therefore, this commit introduces per-order mTHP split
> counters to monitor the frequency of mTHP splits. This will assist
> developers in better analyzing and optimizing system performance.
>
> /sys/kernel/mm/transparent_hugepage/hugepages-<size>/stats
> split_page
> split_page_failed
> deferred_split_page

The deferred_split_page counter may easily go insane with the fix from
https://lore.kernel.org/linux-mm/20240411153232.169560-1-zi.yan@sent.com/

Zi Yan,

Will you submit v2 for this patch soon?


>
> Signed-off-by: Lance Yang <ioworker0@gmail.com>
> ---
> include/linux/huge_mm.h | 3 +++
> mm/huge_memory.c | 14 ++++++++++++--
> 2 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> index 56c7ea73090b..7b9c6590e1f7 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -272,6 +272,9 @@ enum mthp_stat_item {
> MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE,
> MTHP_STAT_ANON_SWPOUT,
> MTHP_STAT_ANON_SWPOUT_FALLBACK,
> + MTHP_STAT_SPLIT_PAGE,
> + MTHP_STAT_SPLIT_PAGE_FAILED,
> + MTHP_STAT_DEFERRED_SPLIT_PAGE,
> __MTHP_STAT_COUNT
> };
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 055df5aac7c3..52db888e47a6 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -557,6 +557,9 @@ DEFINE_MTHP_STAT_ATTR(anon_fault_fallback, MTHP_STAT_ANON_FAULT_FALLBACK);
> DEFINE_MTHP_STAT_ATTR(anon_fault_fallback_charge, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE);
> DEFINE_MTHP_STAT_ATTR(anon_swpout, MTHP_STAT_ANON_SWPOUT);
> DEFINE_MTHP_STAT_ATTR(anon_swpout_fallback, MTHP_STAT_ANON_SWPOUT_FALLBACK);
> +DEFINE_MTHP_STAT_ATTR(split_page, MTHP_STAT_SPLIT_PAGE);
> +DEFINE_MTHP_STAT_ATTR(split_page_failed, MTHP_STAT_SPLIT_PAGE_FAILED);
> +DEFINE_MTHP_STAT_ATTR(deferred_split_page, MTHP_STAT_DEFERRED_SPLIT_PAGE);
>
> static struct attribute *stats_attrs[] = {
> &anon_fault_alloc_attr.attr,
> @@ -564,6 +567,9 @@ static struct attribute *stats_attrs[] = {
> &anon_fault_fallback_charge_attr.attr,
> &anon_swpout_attr.attr,
> &anon_swpout_fallback_attr.attr,
> + &split_page_attr.attr,
> + &split_page_failed_attr.attr,
> + &deferred_split_page_attr.attr,
> NULL,
> };
>
> @@ -3083,7 +3089,7 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
> XA_STATE_ORDER(xas, &folio->mapping->i_pages, folio->index, new_order);
> struct anon_vma *anon_vma = NULL;
> struct address_space *mapping = NULL;
> - bool is_thp = folio_test_pmd_mappable(folio);
> + int order = folio_order(folio);
> int extra_pins, ret;
> pgoff_t end;
> bool is_hzp;
> @@ -3262,8 +3268,10 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
> i_mmap_unlock_read(mapping);
> out:
> xas_destroy(&xas);
> - if (is_thp)
> + if (order >= HPAGE_PMD_ORDER)
> count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
> + count_mthp_stat(order, !ret ? MTHP_STAT_SPLIT_PAGE :
> + MTHP_STAT_SPLIT_PAGE_FAILED);
> return ret;
> }
>
> @@ -3327,6 +3335,8 @@ void deferred_split_folio(struct folio *folio)
> if (list_empty(&folio->_deferred_list)) {
> if (folio_test_pmd_mappable(folio))
> count_vm_event(THP_DEFERRED_SPLIT_PAGE);
> + count_mthp_stat(folio_order(folio),
> + MTHP_STAT_DEFERRED_SPLIT_PAGE);
> list_add_tail(&folio->_deferred_list, &ds_queue->split_queue);
> ds_queue->split_queue_len++;
> #ifdef CONFIG_MEMCG
> --
> 2.33.1
>
>

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