Re: [RFC PATCH 02/12] khugepaged: Generalize alloc_charge_folio()

Dev Jain
2024-12-17T06:09:08Z

On 17/12/24 8:21 am, Baolin Wang wrote:
>
>
> On 2024/12/17 00:50, Dev Jain wrote:
>> Pass order to alloc_charge_folio() and update mTHP statistics.
>>
>> Signed-off-by: Dev Jain <dev.jain@arm.com>
>> ---
>>   include/linux/huge_mm.h |  2 ++
>>   mm/huge_memory.c        |  4 ++++
>>   mm/khugepaged.c         | 13 +++++++++----
>>   3 files changed, 15 insertions(+), 4 deletions(-)
>>
>> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
>> index 93e509b6c00e..8b6d0fed99b3 100644
>> --- a/include/linux/huge_mm.h
>> +++ b/include/linux/huge_mm.h
>> @@ -119,6 +119,8 @@ enum mthp_stat_item {
>>       MTHP_STAT_ANON_FAULT_ALLOC,
>>       MTHP_STAT_ANON_FAULT_FALLBACK,
>>       MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE,
>> +    MTHP_STAT_ANON_COLLAPSE_ALLOC,
>> +    MTHP_STAT_ANON_COLLAPSE_ALLOC_FAILED,
>>       MTHP_STAT_ZSWPOUT,
>>       MTHP_STAT_SWPIN,
>>       MTHP_STAT_SWPIN_FALLBACK,
>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
>> index 2da5520bfe24..2e582fad4c77 100644
>> --- a/mm/huge_memory.c
>> +++ b/mm/huge_memory.c
>> @@ -615,6 +615,8 @@ static struct kobj_attribute _name##_attr =
>> __ATTR_RO(_name)
>>   DEFINE_MTHP_STAT_ATTR(anon_fault_alloc, MTHP_STAT_ANON_FAULT_ALLOC);
>>   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_collapse_alloc,
>> MTHP_STAT_ANON_COLLAPSE_ALLOC);
>> +DEFINE_MTHP_STAT_ATTR(anon_collapse_alloc_failed,
>> MTHP_STAT_ANON_COLLAPSE_ALLOC_FAILED);
>>   DEFINE_MTHP_STAT_ATTR(zswpout, MTHP_STAT_ZSWPOUT);
>>   DEFINE_MTHP_STAT_ATTR(swpin, MTHP_STAT_SWPIN);
>>   DEFINE_MTHP_STAT_ATTR(swpin_fallback, MTHP_STAT_SWPIN_FALLBACK);
>> @@ -636,6 +638,8 @@ static struct attribute *anon_stats_attrs[] = {
>>       &anon_fault_alloc_attr.attr,
>>       &anon_fault_fallback_attr.attr,
>>       &anon_fault_fallback_charge_attr.attr,
>> +    &anon_collapse_alloc_attr.attr,
>> +    &anon_collapse_alloc_failed_attr.attr,
>>   #ifndef CONFIG_SHMEM
>>       &zswpout_attr.attr,
>>       &swpin_attr.attr,
>> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
>> index 95643e6e5f31..02cd424b8e48 100644
>> --- a/mm/khugepaged.c
>> +++ b/mm/khugepaged.c
>> @@ -1073,21 +1073,26 @@ static int __collapse_huge_page_swapin(struct
>> mm_struct *mm,
>>   }
>>     static int alloc_charge_folio(struct folio **foliop, struct
>> mm_struct *mm,
>> -                  struct collapse_control *cc)
>> +                  int order, struct collapse_control *cc)
>>   {
>>       gfp_t gfp = (cc->is_khugepaged ?
>> alloc_hugepage_khugepaged_gfpmask() :
>>                GFP_TRANSHUGE);
>>       int node = hpage_collapse_find_target_node(cc);
>>       struct folio *folio;
>>   -    folio = __folio_alloc(gfp, HPAGE_PMD_ORDER, node,
>> &cc->alloc_nmask);
>> +    folio = __folio_alloc(gfp, order, node, &cc->alloc_nmask);
>>       if (!folio) {
>>           *foliop = NULL;
>>           count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
>> +        if (order != HPAGE_PMD_ORDER)
>> +            count_mthp_stat(order,
>> MTHP_STAT_ANON_COLLAPSE_ALLOC_FAILED);
>>           return SCAN_ALLOC_HUGE_PAGE_FAIL;
>>       }
>>         count_vm_event(THP_COLLAPSE_ALLOC);
>> +    if (order != HPAGE_PMD_ORDER)
>> +        count_mthp_stat(order, MTHP_STAT_ANON_COLLAPSE_ALLOC);
>
> File collapse will also call alloc_charge_folio() to allocate THP, so
> using term '_ANON_' is not suitable for both anon and file collapse.

But currently file collapse will only allocate a PMD-folio, and I have
extended to mTHP only for anon, so it makes sense? Although
I get your point in general...