From: Chen Ridong <chenridong@huaweicloud.com>
To: "Michal Koutný" <mkoutny@suse.com>, "Hui Zhu" <hui.zhu@linux.dev>,
jiayuan.chen@linux.dev
Cc: Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Shakeel Butt <shakeel.butt@linux.dev>,
Muchun Song <muchun.song@linux.dev>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Eduard Zingerman <eddyz87@gmail.com>, Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@fomichev.me>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>, Shuah Khan <shuah@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Miguel Ojeda <ojeda@kernel.org>,
Nathan Chancellor <nathan@kernel.org>,
Kees Cook <kees@kernel.org>, Tejun Heo <tj@kernel.org>,
Jeff Xu <jeffxu@chromium.org>, Jan Hendrik Farr <kernel@jfarr.cc>,
Christian Brauner <brauner@kernel.org>,
Randy Dunlap <rdunlap@infradead.org>,
Brian Gerst <brgerst@gmail.com>,
Masahiro Yamada <masahiroy@kernel.org>,
davem@davemloft.net, Jakub Kicinski <kuba@kernel.org>,
Jesper Dangaard Brouer <hawk@kernel.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
cgroups@vger.kernel.org, bpf@vger.kernel.org,
linux-kselftest@vger.kernel.org, Hui Zhu <zhuhui@kylinos.cn>
Subject: Re: [RFC PATCH v2 0/3] Memory Controller eBPF support
Date: Tue, 30 Dec 2025 21:24:53 +0800 [thread overview]
Message-ID: <31d3fdfa-799e-426b-bb64-42e06392f0b4@huaweicloud.com> (raw)
In-Reply-To: <enlefo5mmoha2htsrvv76tdmj6yum4jan6hgym76adtpxuhvrp@aug6qh3ocde5>
On 2025/12/30 17:49, Michal Koutný wrote:
> Hi Hui.
>
> On Tue, Dec 30, 2025 at 11:01:58AM +0800, Hui Zhu <hui.zhu@linux.dev> wrote:
>> This allows administrators to suppress low-priority cgroups' memory
>> usage based on custom policies implemented in BPF programs.
>
> BTW memory.low was conceived as a work-conserving mechanism for
> prioritization of different workloads. Have you tried that? No need to
> go directly to (high) limits. (<- Main question, below are some
> secondary implementation questions/remarks.)
>
> ...
>> This series introduces a BPF hook that allows reporting
>> additional "pages over high" for specific cgroups, effectively
>> increasing memory pressure and throttling for lower-priority
>> workloads when higher-priority cgroups need resources.
>
> Have you considered hooking into calculate_high_delay() instead? (That
> function has undergone some evolution so it'd seem like the candidate
> for BPFication.)
>
+1
This issue[1] might be resolved by hooking into calculate_high_delay().
[1] https://lore.kernel.org/cgroups/4txrfjc5lqkmydmsesfq3l5drmzdio6pkmtfb64sk3ld6bwkhs@w4dkn76s4dbo/T/#t
> ...
>> 3. Cgroup hierarchy management (inheritance during online/offline)
>
> I see you're copying the program upon memcg creation.
> Configuration copies aren't such a good way to properly handle
> hierarchical behavior.
> I wonder if this could follow the more generic pattern of how BPF progs
> are evaluated in hierarchies, see BPF_F_ALLOW_OVERRIDE and
> BPF_F_ALLOW_MULTI.
>
>
>> Example Results
> ...
>> Results show the low-priority cgroup (/sys/fs/cgroup/low) was
>> significantly throttled:
>> - High-priority cgroup: 21,033,377 bogo ops at 347,825 ops/s
>> - Low-priority cgroup: 11,568 bogo ops at 177 ops/s
>>
>> The stress-ng process in the low-priority cgroup experienced a
>> ~99.9% slowdown in memory operations compared to the
>> high-priority cgroup, demonstrating effective priority
>> enforcement through BPF-controlled memory pressure.
>
> As a demonstrator, it'd be good to compare this with a baseline without
> any extra progs, e.g. show that high-prio performed better and low-prio
> wasn't throttled for nothing.
>
> Thanks,
> Michal
--
Best regards,
Ridong
prev parent reply other threads:[~2025-12-30 13:25 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-30 3:01 Hui Zhu
2025-12-30 3:01 ` [RFC PATCH v2 1/3] mm: memcontrol: Add BPF struct_ops for memory pressure control Hui Zhu
2025-12-30 3:02 ` [RFC PATCH v2 2/3] selftests/bpf: Add tests for memcg_bpf_ops Hui Zhu
2025-12-30 3:02 ` [RFC PATCH v2 3/3] samples/bpf: Add memcg priority control example Hui Zhu
2025-12-30 9:49 ` [RFC PATCH v2 0/3] Memory Controller eBPF support Michal Koutný
2025-12-30 13:24 ` Chen Ridong [this message]
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