From: Tejun Heo <tj@kernel.org>
To: Yafang Shao <laoar.shao@gmail.com>
Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
eddyz87@gmail.com, memxor@gmail.com, mingo@redhat.com,
peterz@infradead.org, juri.lelli@redhat.com,
vincent.guittot@linaro.org, akpm@linux-foundation.org,
david@kernel.org, gourry@gourry.net, hannes@cmpxchg.org,
mkoutny@suse.com, shakeel.butt@linux.dev,
roman.gushchin@linux.dev, yu.c.chen@intel.com,
zhao1.liu@intel.com, bpf@vger.kernel.org, linux-mm@kvack.org,
cgroups@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v2 0/3] BPF-based per-cgroup NUMA balancing mode selection
Date: Tue, 13 Oct 2026 08:02:33 -1000 [thread overview]
Message-ID: <3eda489898ebf7c848ce61760af745d9@kernel.org> (raw)
In-Reply-To: <CALOAHbBE_1ssK_26c-UY7N6WxhkVNpB6v9WACVGaOiWZ5zchCA@mail.gmail.com>
Hello,
On Tue, Oct 13, 2026 at 10:16:32AM +0800, Yafang Shao wrote:
> Part of the consults are keyed on struct folio rather than struct
> task_struct: the folio surface answers from the folio's memcg, the
> owner's request, not the touching task's.
Right, and I take the prctl() point too. It's stable uAPI and too rigid
a bar for this.
My suggestion is to start smaller. The op doesn't compute anything
from its inputs. It returns a fixed mode per cgroup, and you don't
need struct_ops for that.
A kfunc that takes a cgid and a value would do: -1 for the system
setting, otherwise the existing NUMA_BALANCING_* bitmask stored per
cgroup. Task callsites read it through the task's cgroup, folio
callsites through folio_memcg(). Same capability for the use case in
the cover letter, a per-cgroup field and minimal plumbing, and the
kfunc can grow later if a real decision-time policy shows up.
Thanks.
--
tejun
next prev parent reply other threads:[~2026-10-13 18:02 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-12 12:04 [RFC PATCH v2 0/3] BPF-based per-cgroup NUMA balancing mode selection Yafang Shao
2026-10-12 12:04 ` [RFC PATCH v2 1/3] sched: add helpers for numa balancing Yafang Shao
2026-10-12 12:19 ` sashiko-bot
2026-10-12 14:23 ` Yafang Shao
2026-10-13 7:38 ` David Hildenbrand (Arm)
2026-10-13 9:14 ` Yafang Shao
2026-10-12 12:04 ` [RFC PATCH v2 2/3] sched: add per-cgroup NUMA balancing mode selection via BPF Yafang Shao
2026-10-12 12:25 ` sashiko-bot
2026-10-12 13:55 ` Yafang Shao
2026-10-12 12:04 ` [RFC PATCH v2 3/3] selftests/bpf: add tests for the bpf_numab_ops struct_ops Yafang Shao
2026-10-12 12:13 ` sashiko-bot
2026-10-12 17:51 ` [RFC PATCH v2 0/3] BPF-based per-cgroup NUMA balancing mode selection Tejun Heo
2026-10-13 2:16 ` Yafang Shao
2026-10-13 18:02 ` Tejun Heo [this message]
2026-10-13 15:49 ` Gregory Price
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