Re: [v7 PATCH 09/12] mm: vmscan: use per memcg nr_deferred of shrinker

[Kirill Tkhai <ktkhai@virtuozzo.com>]

On 10.02.2021 04:52, Yang Shi wrote:
> On Tue, Feb 9, 2021 at 5:27 PM Roman Gushchin <guro@fb.com> wrote:
>>
>> On Tue, Feb 09, 2021 at 09:46:43AM -0800, Yang Shi wrote:
>>> Use per memcg's nr_deferred for memcg aware shrinkers.  The shrinker's nr_deferred
>>> will be used in the following cases:
>>>     1. Non memcg aware shrinkers
>>>     2. !CONFIG_MEMCG
>>>     3. memcg is disabled by boot parameter
>>>
>>> Signed-off-by: Yang Shi <shy828301@gmail.com>
>>> ---
>>>  mm/vmscan.c | 78 ++++++++++++++++++++++++++++++++++++++++++++---------
>>>  1 file changed, 66 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>>> index d4b030a0b2a9..748aa6e90f83 100644
>>> --- a/mm/vmscan.c
>>> +++ b/mm/vmscan.c
>>> @@ -368,6 +368,24 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker)
>>>       up_write(&shrinker_rwsem);
>>>  }
>>>
>>> +static long count_nr_deferred_memcg(int nid, struct shrinker *shrinker,
>>> +                                 struct mem_cgroup *memcg)
>>
>> "Count" is not associated with xchg() semantics in my head, but I don't know
>> what's the better version. Maybe steal or pop?
> 
> It is used to retrieve the nr_deferred value. I don't think "steal" or
> "pop" helps understand. Actually "count" is borrowed from
> count_objects() method of shrinker.

I'd also voted for another name.

xchg_nr_deferred() or steal/pop sound better for me.