linux-kernel - Re: [RFC PATCH 1/8] mm: fix shmem swapout statistic

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Date: Wed, 22 May 2024 15:54:00 +0800
From: Baolin Wang <baolin.wang@...ux.alibaba.com>
To: "Huang, Ying" <ying.huang@...el.com>
Cc: akpm@...ux-foundation.org, hughd@...gle.com, willy@...radead.org,
 david@...hat.com, ioworker0@...il.com, hrisl@...nel.org,
 p.raghav@...sung.com, da.gomez@...sung.com, wangkefeng.wang@...wei.com,
 21cnbao@...il.com, ryan.roberts@....com, shy828301@...il.com,
 ziy@...dia.com, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 1/8] mm: fix shmem swapout statistic



On 2024/5/22 15:16, Huang, Ying wrote:
> Baolin Wang <baolin.wang@...ux.alibaba.com> writes:
> 
>> As we know, shmem not only supports the sharing of anonymous pages, but also
>> the RAM-based temporary filesystem. Therefore, shmem swapouts should not be
>> marked as anonymous swapout statistics. Fix it by adding folio_test_anon().
>>
>> Fixes: d0f048ac39f6 ("mm: add per-order mTHP anon_swpout and anon_swpout_fallback counters")
>> Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
>> ---
>>   mm/page_io.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/mm/page_io.c b/mm/page_io.c
>> index 46c603dddf04..b181b81f39e3 100644
>> --- a/mm/page_io.c
>> +++ b/mm/page_io.c
>> @@ -217,7 +217,9 @@ static inline void count_swpout_vm_event(struct folio *folio)
>>   		count_memcg_folio_events(folio, THP_SWPOUT, 1);
>>   		count_vm_event(THP_SWPOUT);
>>   	}
>> -	count_mthp_stat(folio_order(folio), MTHP_STAT_ANON_SWPOUT);
>> +
>> +	if (folio_test_anon(folio))
>> +		count_mthp_stat(folio_order(folio), MTHP_STAT_ANON_SWPOUT);
> 
> Do we need to distinguish anonymous swapout and non-anonymous swapout?
> IMHO, we don't.  Just like we have done for small folio and THP.

Yes, old counters did not add 'anon_' prefix.

> If so, how about fix this in another direction?  That is, remove "ANON"
> from mTHP swapout statistics?

This sounds good to me. And I will separate out an individual patch with 
your suggestion. Thanks.