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Date: Mon, 1 Jul 2024 18:36:41 +0800
From: Lance Yang <ioworker0@...il.com>
To: Baolin Wang <baolin.wang@...ux.alibaba.com>
Cc: Barry Song <21cnbao@...il.com>, akpm@...ux-foundation.org, dj456119@...il.com,
ryan.roberts@....com, david@...hat.com, shy828301@...il.com, ziy@...dia.com,
libang.li@...group.com, linux-kernel@...r.kernel.org, linux-mm@...ck.org,
Mingzhe Yang <mingzhe.yang@...com>
Subject: Re: [PATCH v2 1/2] mm: add per-order mTHP split counters
Hi Baolin,
Thanks for taking time to review!
On Mon, Jul 1, 2024 at 10:23 AM Baolin Wang
<baolin.wang@...ux.alibaba.com> wrote:
>
>
>
> On 2024/7/1 08:02, Barry Song wrote:
> > On Sat, Jun 29, 2024 at 1:09 AM Lance Yang <ioworker0@...il.com> wrote:
> >>
> >> Currently, the split counters in THP statistics no longer include
> >> PTE-mapped mTHP. Therefore, we propose introducing per-order mTHP split
> >> counters to monitor the frequency of mTHP splits. This will help developers
> >> better analyze and optimize system performance.
> >>
> >> /sys/kernel/mm/transparent_hugepage/hugepages-<size>/stats
> >> split
> >> split_failed
> >> split_deferred
> >>
> >> Signed-off-by: Mingzhe Yang <mingzhe.yang@...com>
> >> Signed-off-by: Lance Yang <ioworker0@...il.com>
> >
> > Personally, I'm not convinced that using a temporary variable order
> > makes the code
> > more readable. Functions like folio_test_pmd_mappable() seem more readable to
> > me. In any case, it's a minor issue.
>
> Yes, I have the same opinion as Barry. With that:
> Reviewed-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
Thanks again for your opinion!
Lance
>
>
> > Acked-by: Barry Song <baohua@...nel.org>
> >
> >> ---
> >> include/linux/huge_mm.h | 3 +++
> >> mm/huge_memory.c | 19 ++++++++++++++-----
> >> 2 files changed, 17 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> >> index 212cca384d7e..cee3c5da8f0e 100644
> >> --- a/include/linux/huge_mm.h
> >> +++ b/include/linux/huge_mm.h
> >> @@ -284,6 +284,9 @@ enum mthp_stat_item {
> >> MTHP_STAT_FILE_ALLOC,
> >> MTHP_STAT_FILE_FALLBACK,
> >> MTHP_STAT_FILE_FALLBACK_CHARGE,
> >> + MTHP_STAT_SPLIT,
> >> + MTHP_STAT_SPLIT_FAILED,
> >> + MTHP_STAT_SPLIT_DEFERRED,
> >> __MTHP_STAT_COUNT
> >> };
> >>
> >> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> >> index c7ce28f6b7f3..a633206375af 100644
> >> --- a/mm/huge_memory.c
> >> +++ b/mm/huge_memory.c
> >> @@ -559,6 +559,9 @@ DEFINE_MTHP_STAT_ATTR(swpout_fallback, MTHP_STAT_SWPOUT_FALLBACK);
> >> DEFINE_MTHP_STAT_ATTR(file_alloc, MTHP_STAT_FILE_ALLOC);
> >> DEFINE_MTHP_STAT_ATTR(file_fallback, MTHP_STAT_FILE_FALLBACK);
> >> DEFINE_MTHP_STAT_ATTR(file_fallback_charge, MTHP_STAT_FILE_FALLBACK_CHARGE);
> >> +DEFINE_MTHP_STAT_ATTR(split, MTHP_STAT_SPLIT);
> >> +DEFINE_MTHP_STAT_ATTR(split_failed, MTHP_STAT_SPLIT_FAILED);
> >> +DEFINE_MTHP_STAT_ATTR(split_deferred, MTHP_STAT_SPLIT_DEFERRED);
> >>
> >> static struct attribute *stats_attrs[] = {
> >> &anon_fault_alloc_attr.attr,
> >> @@ -569,6 +572,9 @@ static struct attribute *stats_attrs[] = {
> >> &file_alloc_attr.attr,
> >> &file_fallback_attr.attr,
> >> &file_fallback_charge_attr.attr,
> >> + &split_attr.attr,
> >> + &split_failed_attr.attr,
> >> + &split_deferred_attr.attr,
> >> NULL,
> >> };
> >>
> >> @@ -3068,7 +3074,7 @@ 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;
> >> @@ -3076,7 +3082,7 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
> >> VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
> >> VM_BUG_ON_FOLIO(!folio_test_large(folio), folio);
> >>
> >> - if (new_order >= folio_order(folio))
> >> + if (new_order >= order)
> >> return -EINVAL;
> >>
> >> if (folio_test_anon(folio)) {
> >> @@ -3253,8 +3259,9 @@ 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 : MTHP_STAT_SPLIT_FAILED);
> >> return ret;
> >> }
> >>
> >> @@ -3278,13 +3285,14 @@ void deferred_split_folio(struct folio *folio)
> >> #ifdef CONFIG_MEMCG
> >> struct mem_cgroup *memcg = folio_memcg(folio);
> >> #endif
> >> + int order = folio_order(folio);
> >> unsigned long flags;
> >>
> >> /*
> >> * Order 1 folios have no space for a deferred list, but we also
> >> * won't waste much memory by not adding them to the deferred list.
> >> */
> >> - if (folio_order(folio) <= 1)
> >> + if (order <= 1)
> >> return;
> >>
> >> /*
> >> @@ -3305,8 +3313,9 @@ void deferred_split_folio(struct folio *folio)
> >>
> >> spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
> >> if (list_empty(&folio->_deferred_list)) {
> >> - if (folio_test_pmd_mappable(folio))
> >> + if (order >= HPAGE_PMD_ORDER)
> >> count_vm_event(THP_DEFERRED_SPLIT_PAGE);
> >> + count_mthp_stat(order, MTHP_STAT_SPLIT_DEFERRED);
> >> list_add_tail(&folio->_deferred_list, &ds_queue->split_queue);
> >> ds_queue->split_queue_len++;
> >> #ifdef CONFIG_MEMCG
> >> --
> >> 2.45.2
> >>
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