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

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Message-ID: <87v8ack889.fsf@yhuang6-desk2.ccr.corp.intel.com>
Date:   Wed, 08 Nov 2023 15:35:50 +0800
From:   "Huang, Ying" <ying.huang@...el.com>
To:     Huan Yang <link@...o.com>
Cc:     Tejun Heo <tj@...nel.org>, Zefan Li <lizefan.x@...edance.com>,
        "Johannes Weiner" <hannes@...xchg.org>,
        Jonathan Corbet <corbet@....net>,
        Michal Hocko <mhocko@...nel.org>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Shakeel Butt <shakeelb@...gle.com>,
        Muchun Song <muchun.song@...ux.dev>,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Hildenbrand <david@...hat.com>,
        "Matthew Wilcox" <willy@...radead.org>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Peter Xu <peterx@...hat.com>,
        "Vishal Moola (Oracle)" <vishal.moola@...il.com>,
        Yosry Ahmed <yosryahmed@...gle.com>,
        "Liu Shixin" <liushixin2@...wei.com>,
        Hugh Dickins <hughd@...gle.com>, <cgroups@...r.kernel.org>,
        <linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-mm@...ck.org>, <opensource.kernel@...o.com>
Subject: Re: [RFC 0/4] Introduce unbalance proactive reclaim

Huan Yang <link@...o.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?

> 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?

> 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.

>  .../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