linux-kernel - Re: [PATCH 4/7] mm: shmem: extend shmem_partial_swap

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Date: Tue, 11 Jun 2024 10:59:27 +0800
From: Baolin Wang <baolin.wang@...ux.alibaba.com>
To: Daniel Gomez <da.gomez@...sung.com>
Cc: "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
 "hughd@...gle.com" <hughd@...gle.com>,
 "willy@...radead.org" <willy@...radead.org>,
 "david@...hat.com" <david@...hat.com>,
 "wangkefeng.wang@...wei.com" <wangkefeng.wang@...wei.com>,
 "chrisl@...nel.org" <chrisl@...nel.org>,
 "ying.huang@...el.com" <ying.huang@...el.com>,
 "21cnbao@...il.com" <21cnbao@...il.com>,
 "ryan.roberts@....com" <ryan.roberts@....com>,
 "shy828301@...il.com" <shy828301@...il.com>, "ziy@...dia.com"
 <ziy@...dia.com>, "ioworker0@...il.com" <ioworker0@...il.com>,
 Pankaj Raghav <p.raghav@...sung.com>, "linux-mm@...ck.org"
 <linux-mm@...ck.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/7] mm: shmem: extend shmem_partial_swap_usage() to
 support large folio swap



On 2024/6/10 22:53, Daniel Gomez wrote:
> Hi Baolin,
> On Thu, Jun 06, 2024 at 07:58:54PM +0800, Baolin Wang wrote:
>> To support shmem large folio swapout in the following patches, using
>> xa_get_order() to get the order of the swap entry to calculate the swap
>> usage of shmem.
>>
>> Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
>> ---
>>   mm/shmem.c | 7 +++++--
>>   1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/mm/shmem.c b/mm/shmem.c
>> index eefdf5c61c04..0ac71580decb 100644
>> --- a/mm/shmem.c
>> +++ b/mm/shmem.c
>> @@ -865,13 +865,16 @@ unsigned long shmem_partial_swap_usage(struct address_space *mapping,
>>   	struct page *page;
>>   	unsigned long swapped = 0;
>>   	unsigned long max = end - 1;
>> +	int order;
>>   
>>   	rcu_read_lock();
>>   	xas_for_each(&xas, page, max) {
>>   		if (xas_retry(&xas, page))
>>   			continue;
>> -		if (xa_is_value(page))
>> -			swapped++;
>> +		if (xa_is_value(page)) {
>> +			order = xa_get_order(xas.xa, xas.xa_index);
>> +			swapped += 1 << order;
> 
> I'd get rid of order and simply do:
> 
> 	swapped += 1UL << xa_get_order()

OK. Will do.