linux-kernel - Re: [RFC PATCH -next 0/7] Introduce heat-level memcg reclaim

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <bfba09cf-89d8-4ec1-9299-7128d79569ff@huaweicloud.com>
Date: Thu, 29 Jan 2026 19:25:01 +0800
From: Chen Ridong <chenridong@...weicloud.com>
To: akpm@...ux-foundation.org, axelrasmussen@...gle.com, yuanchu@...gle.com,
 weixugc@...gle.com, david@...nel.org, lorenzo.stoakes@...cle.com,
 Liam.Howlett@...cle.com, vbabka@...e.cz, rppt@...nel.org, surenb@...gle.com,
 mhocko@...e.com, corbet@....net, skhan@...uxfoundation.org,
 hannes@...xchg.org, roman.gushchin@...ux.dev, shakeel.butt@...ux.dev,
 muchun.song@...ux.dev, zhengqi.arch@...edance.com
Cc: linux-mm@...ck.org, linux-doc@...r.kernel.org,
 linux-kernel@...r.kernel.org, cgroups@...r.kernel.org, lujialin4@...wei.com,
 ryncsn@...il.com
Subject: Re: [RFC PATCH -next 0/7] Introduce heat-level memcg reclaim



On 2026/1/20 21:42, Chen Ridong wrote:
> From: Chen Ridong <chenridong@...wei.com>
> 
> The memcg LRU was originally introduced to improve scalability during
> global reclaim, but it only supports gen lru global reclaim and its
> implementation has become complex. Moreover, it has caused performance
> regressions when dealing with a large number of memory cgroups [1].
> 
> Previous attempts to remove memcg LRU by switching back to iteration
> implementation brought performance regression [3].
> 
> This series introduces a per-memcg heat level mechanism for reclaim,
> aiming to unify gen lru and traditional LRU global reclaim. The core
> idea is to track per-node per-memcg reclaim state, including heat,
> last_decay, and last_refault. Three reclaim heat levels are defined:
> cold, warm, and hot. Cold memcgs are reclaimed first; only if cold
> memcgs cannot reclaim enough pages, warm memcgs become eligible for
> reclaim. Hot memcgs are reclaimed last.
> 
> While the heat level design can be applied to all memcg reclaim scenarios,
> this series takes a conservative approach and initially applies it only
> to global reclaim. The first few patches introduce the heat level
> infrastructure and apply it to traditional LRU global reclaim. The
> subsequent patches gradually migrate gen lru global reclaim to the
> heat-level-based approach, with the final patch combining shrink_many
> into shrink_node_memcgs to complete the transition.
> 
> Performance results show significant improvements:
> 
> Traditional LRU results (2-hour run of test [2]):
> Throughput (number of requests)         before     after        Change
> Total                                   1,734,169  2,353,717    +35%
> 
> Gen LRU results (24-hour run of test [2]):
> Throughput (number of requests)         before     after        Change
> Total                                   22,879,701 25,331,956   +10%
> 
> The performance tests are based on next branch commit:
> commit ef0d146624b0 ("Add linux-next specific files for 20251219")
> 
> This series has been rebased on next-20260119:
> commit d08c85ac8894 ("Add linux-next specific files for 20260119")
> 
> [1] https://lore.kernel.org/r/20251126171513.GC135004@cmpxchg.org
> [2] https://lore.kernel.org/r/20221222041905.2431096-7-yuzhao@google.com
> [3] https://lore.kernel.org/lkml/20251224073032.161911-1-chenridong@huaweicloud.com/
> 
> Chen Ridong (7):
>   vmscan: add memcg heat level for reclaim
>   mm/mglru: make calls to flush_reclaim_state() similar for MGLRU and
>     non-MGLRU
>   mm/mglru: rename should_abort_scan to lru_gen_should_abort_scan
>   mm/mglru: extend lru_gen_shrink_lruvec to support root reclaim
>   mm/mglru: combine shrink_many into shrink_node_memcgs
>   mm/mglru: remove memcg disable handling from lru_gen_shrink_node
>   mm/mglru: remove memcg lru
> 
>  Documentation/mm/multigen_lru.rst |  30 --
>  include/linux/memcontrol.h        |   7 +
>  include/linux/mmzone.h            |  89 -----
>  mm/memcontrol-v1.c                |   6 -
>  mm/memcontrol.c                   |   7 +-
>  mm/mm_init.c                      |   1 -
>  mm/vmscan.c                       | 547 ++++++++++++------------------
>  7 files changed, 231 insertions(+), 456 deletions(-)
> 

Hi, Johannes and Shakeel,

I would appreciate it if you could share your thoughts on this series.

-- 
Best regards,
Ridong