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Date: Thu, 25 Apr 2024 01:58:53 +0800
From: Bang Li <libang.linux@...il.com>
To: Lance Yang <ioworker0@...il.com>
Cc: akpm@...ux-foundation.org, 21cnbao@...il.com, ryan.roberts@....com,
david@...hat.com, baolin.wang@...ux.alibaba.com,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
Bang Li <libang.linux@...il.com>
Subject: Re: [PATCH 1/2] mm: add per-order mTHP split counters
Hey, sorry for making noise, there was something wrong with the format of
the last email.
On 2024/4/25 1:12, Bang Li wrote:
> Hey Lance,
>
> On 2024/4/24 21:51, Lance Yang 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
>>
>> Signed-off-by: Lance Yang <ioworker0@...il.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
>
> My opinion can be ignored :). Would it be better to modify the
> deferred_split_folio
> function as follows? I'm not sure.
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c index
> 055df5aac7c3..e8562e8630b1 100644 --- a/mm/huge_memory.c +++
> b/mm/huge_memory.c @@ -3299,12 +3299,13 @@ void
> deferred_split_folio(struct folio *folio) struct mem_cgroup *memcg =
> folio_memcg(folio); #endif unsigned long flags; + int order =
> folio_order(folio); /* * 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; /* @@ -3325,8 +3326,9 @@ 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_DEFERRED_SPLIT_PAGE); list_add_tail(&folio->_deferred_list,
> &ds_queue->split_queue); ds_queue->split_queue_len++; #ifdef
> CONFIG_MEMCG thanks,
> bang
>
My opinion can be ignored :). Would it be better to modify the
deferred_split_folio
function as follows? I'm not sure.
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 055df5aac7c3..e8562e8630b1 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3299,12 +3299,13 @@ void deferred_split_folio(struct folio *folio)
struct mem_cgroup *memcg = folio_memcg(folio);
#endif
unsigned long flags;
+ int order = folio_order(folio);
/*
* 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;
/*
@@ -3325,8 +3326,9 @@ 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_DEFERRED_SPLIT_PAGE);
list_add_tail(&folio->_deferred_list,
&ds_queue->split_queue);
ds_queue->split_queue_len++;
#ifdef CONFIG_MEMCG
thanks,
bang
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