Re: [RFC 0/4] Introduce unbalance proactive reclaim

[Huan Yang <link@vivo.com>]

HI Huang, Ying

Thanks for reply.

在 2023/11/8 15:35, Huang, Ying 写道:
> Huan Yang <link@vivo.com> writes:
>
>> In some cases, we need to selectively reclaim file pages or anonymous
>> pages in an unbalanced manner.
>>
>> For example, when an application is pushed to the background and frozen,
>> it may not be opened for a long time, and we can safely reclaim the
>> application's anonymous pages, but we do not want to touch the file pages.
>>
>> This patchset extends the proactive reclaim interface to achieve
>> unbalanced reclamation. Users can control the reclamation tendency by
>> inputting swappiness under the original interface. Specifically, users
>> can input special values to extremely reclaim specific pages.
>  From mem_cgroup_swappiness(), cgroupv2 doesn't have per-cgroup
> swappiness.  So you need to add that firstly?
Sorry for this mistake, we always work on cgroupv1, so, not notice
this commit 4550c4e, thank your for point that.

I see this commit comment that `that's a different discussion`, but,
to implements this, I will try add.

>
>> Example:
>>    	echo "1G" 200 > memory.reclaim (only reclaim anon)
>> 	  echo "1G" 0  > memory.reclaim (only reclaim file)
>> 	  echo "1G" 1  > memory.reclaim (only reclaim file)
>>
>> Note that when performing unbalanced reclamation, the cgroup swappiness
>> will be temporarily adjusted dynamically to the input value. Therefore,
>> if the cgroup swappiness is further modified during runtime, there may
>> be some errors.
> If cgroup swappiness will be adjusted temporarily, why not just change
> it via a script before/after proactive reclaiming?
IMO, this unbalance reclaim only takes effect for a single command,
so if it is pre-set using a script, the judgment of the reclamation tendency
may become complicated.

So, do you mean avoid use cgroup swappiness, just type anon or file to 
control
this extreme unbalanced reclamation?

>
>> However, this is acceptable because the interface is dynamically called
>> by the user and the timing should be controlled by the user.
>>
>> This patchset did not implement the type-based reclamation as expected
>> in the documentation.(anon or file) Because in addition to extreme unbalanced
>> reclamation, this patchset can also adapt to the reclamation tendency
>> allocated according to swappiness, which is more flexible.
>>
>> Self test
>> ========
>> After applying the following patches and myself debug patch, my self-test
>> results are as follows:
>>
>> 1. LRU test
>> ===========
>>    a. Anon unbalance reclaim
>>    ```
>>    cat memory.stat | grep anon
>>      inactive_anon 7634944
>>      active_anon 7741440
>>
>>    echo "200M" 200 > memory.reclaim
>>
>>    cat memory.stat | grep anon
>>      inactive_anon 0
>>      active_anon 0
>>
>>    cat memory.reclaim_stat_summary(self debug interface)
>>      [22368]sh total reclaimed 0 file, 3754 anon, covered item=0
>>    ```
>>
>>    b. File unbalance reclaim
>>    ```
>>    cat memory.stat | grep file
>>      inactive_file 82862080
>>      active_file 48664576
>>
>>    echo "100M" 0 > memory.reclaim
>>    cat memory.stat | grep file
>>      inactive_file 34164736
>>      active_file 18370560
>>
>>    cat memory.reclaim_stat_summary(self debug interface)
>>      [22368]sh total reclaimed 13732 file, 0 anon, covered item=0
>>    ```
>>
>> 2. MGLRU test
>> ============
>> a. Anon unbalance reclaim
>> ```
>> echo y > /sys/kernel/mm/lru_gen/enabled
>> cat /sys/kernel/mm/lru_gen/enabled
>>    0x0003
>>
>> cat memory.stat | grep anon
>>    inactive_anon 17653760
>>    active_anon 1740800
>>
>> echo "100M" 200 > memory.reclaim
>>
>> cat memory.reclaim_stat_summary
>>    [8251]sh total reclaimed 0 file, 5393 anon, covered item=0
>> ```
>>
>> b. File unbalance reclaim
>> ```
>> cat memory.stat | grep file
>>    inactive_file 17858560
>>    active_file 5943296
>>
>> echo "100M" 0 > memory.reclaim
>>
>> cat memory.stat | grep file
>>    inactive_file 491520
>>    active_file 2764800
>> cat memory.reclaim_stat_summary
>>    [8251]sh total reclaimed 5230 file, 0 anon, covered item=0
>> ```
>>
>> Patch 1-3 implement the functionality described above.
>> Patch 4 aims to implement proactive reclamation to the cgroupv1 interface
>> for use on Android.
>>
>> Huan Yang (4):
>>    mm: vmscan: LRU unbalance cgroup reclaim
>>    mm: multi-gen LRU: MGLRU unbalance reclaim
>>    mm: memcg: implement unbalance proactive reclaim
>>    mm: memcg: apply proactive reclaim into cgroupv1
> We will not add new features to cgroupv1 in upstream.
Thx for point that. If this feature is worth further updating, the next 
patchset
will remove this patch.
>
>>   .../admin-guide/cgroup-v1/memory.rst          |  38 +++++-
>>   Documentation/admin-guide/cgroup-v2.rst       |  16 ++-
>>   include/linux/swap.h                          |   1 +
>>   mm/memcontrol.c                               | 126 ++++++++++++------
>>   mm/vmscan.c                                   |  38 +++++-
>>   5 files changed, 169 insertions(+), 50 deletions(-)
> --
> Best Regards,
> Huang, Ying

Thanks,
Huan Yang