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SubjectRe: [RFC PATCH 5/5] mm: shmem: add anonymous share mTHP counters
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On 2024/4/23 09:17, Barry Song wrote:
> On Mon, Apr 22, 2024 at 3:03 PM Baolin Wang
> <baolin.wang@linux.alibaba.com> wrote:
>>
>> Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
>> ---
>> include/linux/huge_mm.h | 2 ++
>> mm/huge_memory.c | 4 ++++
>> mm/shmem.c | 5 ++++-
>> 3 files changed, 10 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
>> index 26b6fa98d8ac..67b9c1acad31 100644
>> --- a/include/linux/huge_mm.h
>> +++ b/include/linux/huge_mm.h
>> @@ -270,6 +270,8 @@ enum mthp_stat_item {
>> MTHP_STAT_ANON_SWPOUT,
>> MTHP_STAT_ANON_SWPOUT_FALLBACK,
>> MTHP_STAT_ANON_SWPIN_REFAULT,
>> + MTHP_STAT_SHMEM_ANON_ALLOC,
>> + MTHP_STAT_SHMEM_ANON_ALLOC_FALLBACK,
>
> not quite sure about this. for 2MB pmd-mapped THP shmem, we count them
> as FILE_THP.
> here we are counting as SHMEM_ANON. To me, SHMEM_ANON is more correct but
> it doesn't align with pmd-mapped THP. David, Ryan, what do you think?

Thanks for reviewing.

IMO, I think both approaches are acceptable, which also reflects the
dual nature of anonymous shared pages: on the one hand they are
anonymous pages, and on the other hand, they are backed by a pseudo
file. From the user's perspective, I prefer to use the term "anonymous
shmem", which can be distinguished from the real file-backed THP.

Anyway, let's see what others think.

>> __MTHP_STAT_COUNT
>> };
>>
>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
>> index 9e52c0db7580..dc15240c1ab3 100644
>> --- a/mm/huge_memory.c
>> +++ b/mm/huge_memory.c
>> @@ -557,6 +557,8 @@ DEFINE_MTHP_STAT_ATTR(anon_alloc_fallback, MTHP_STAT_ANON_ALLOC_FALLBACK);
>> 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(anon_swpin_refault, MTHP_STAT_ANON_SWPIN_REFAULT);
>> +DEFINE_MTHP_STAT_ATTR(shmem_anon_alloc, MTHP_STAT_SHMEM_ANON_ALLOC);
>> +DEFINE_MTHP_STAT_ATTR(shmem_anon_alloc_fallback, MTHP_STAT_SHMEM_ANON_ALLOC_FALLBACK);
>>
>> static struct attribute *stats_attrs[] = {
>> &anon_alloc_attr.attr,
>> @@ -564,6 +566,8 @@ static struct attribute *stats_attrs[] = {
>> &anon_swpout_attr.attr,
>> &anon_swpout_fallback_attr.attr,
>> &anon_swpin_refault_attr.attr,
>> + &shmem_anon_alloc_attr.attr,
>> + &shmem_anon_alloc_fallback_attr.attr,
>> NULL,
>> };
>>
>> diff --git a/mm/shmem.c b/mm/shmem.c
>> index 8b009e7040b2..4a0aa75ab29c 100644
>> --- a/mm/shmem.c
>> +++ b/mm/shmem.c
>> @@ -1706,11 +1706,14 @@ static struct folio *shmem_alloc_and_add_folio(struct vm_fault *vmf,
>> pages = 1 << order;
>> index = round_down(index, pages);
>> folio = shmem_alloc_hugefolio(gfp, info, index, order);
>> - if (folio)
>> + if (folio) {
>> + count_mthp_stat(order, MTHP_STAT_SHMEM_ANON_ALLOC);
>> goto allocated;
>> + }
>>
>> if (pages == HPAGE_PMD_NR)
>> count_vm_event(THP_FILE_FALLBACK);
>> + count_mthp_stat(order, MTHP_STAT_SHMEM_ANON_ALLOC_FALLBACK);
>> order = next_order(&orders, order);
>> }
>> } else {
>> --
>> 2.39.3
>>
>
> Thanks
> Barry

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