Re: [PATCH v5 6/6] mm: shmem: add mTHP counters for anonymous shmem

[Baolin Wang <baolin.wang@linux.alibaba.com>]

On 2024/6/12 16:04, Lance Yang wrote:
> Hi Baolin,
> 
> On Tue, Jun 11, 2024 at 6:11 PM Baolin Wang
> <baolin.wang@linux.alibaba.com> wrote:
>>
>> Add mTHP counters for anonymous shmem.
>>
>> Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
>> ---
>>   include/linux/huge_mm.h |  3 +++
>>   mm/huge_memory.c        |  6 ++++++
>>   mm/shmem.c              | 18 +++++++++++++++---
>>   3 files changed, 24 insertions(+), 3 deletions(-)
>>
>> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
>> index 909cfc67521d..212cca384d7e 100644
>> --- a/include/linux/huge_mm.h
>> +++ b/include/linux/huge_mm.h
>> @@ -281,6 +281,9 @@ enum mthp_stat_item {
>>          MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE,
>>          MTHP_STAT_SWPOUT,
>>          MTHP_STAT_SWPOUT_FALLBACK,
>> +       MTHP_STAT_FILE_ALLOC,
>> +       MTHP_STAT_FILE_FALLBACK,
>> +       MTHP_STAT_FILE_FALLBACK_CHARGE,
>>          __MTHP_STAT_COUNT
>>   };
>>
>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
>> index 1360a1903b66..3fbcd77f5957 100644
>> --- a/mm/huge_memory.c
>> +++ b/mm/huge_memory.c
>> @@ -555,6 +555,9 @@ 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(swpout, MTHP_STAT_SWPOUT);
>>   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);
>>
>>   static struct attribute *stats_attrs[] = {
>>          &anon_fault_alloc_attr.attr,
>> @@ -562,6 +565,9 @@ static struct attribute *stats_attrs[] = {
>>          &anon_fault_fallback_charge_attr.attr,
>>          &swpout_attr.attr,
>>          &swpout_fallback_attr.attr,
>> +       &file_alloc_attr.attr,
>> +       &file_fallback_attr.attr,
>> +       &file_fallback_charge_attr.attr,
>>          NULL,
>>   };
>>
>> diff --git a/mm/shmem.c b/mm/shmem.c
>> index f5469c357be6..99bd3c34f0fb 100644
>> --- a/mm/shmem.c
>> +++ b/mm/shmem.c
>> @@ -1773,6 +1773,9 @@ static struct folio *shmem_alloc_and_add_folio(struct vm_fault *vmf,
>>
>>                          if (pages == HPAGE_PMD_NR)
>>                                  count_vm_event(THP_FILE_FALLBACK);
>> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
>> +                       count_mthp_stat(order, MTHP_STAT_FILE_FALLBACK);
>> +#endif
> 
> Using the conditional compilation directives here is a bit weird :)
> Would there be any issues if we were to drop them?

Will cause building errors if CONFIG_TRANSPARENT_HUGEPAGE is not enabled.

> 
> Since THP_FILE_FALLBACK is working as expected, MTHP_STAT_FILE_FALLBACK
> should work as well without the conditional compilation directives, IIUC.

No, you should take a look at how count_mthp_stat() is defined :)