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

[Huan Yang]

HI Huang, Ying

Thanks for reply.

在 2023/11/8 15:35, Huang, Ying 写道:
> Huan Yang <link@xxxxxxxx> 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