From: Tejun Heo <tj@kernel.org>
To: Qiliang Yuan <odys.yuan@gmail.com>
Cc: christian.koenig@amd.com, ray.huang@amd.com,
matthew.auld@intel.com, matthew.brost@intel.com,
maarten.lankhorst@linux.intel.com, mripard@kernel.org,
tzimmermann@suse.de, airlied@gmail.com, simona@ffwll.ch,
tj@kernel.org, hannes@cmpxchg.org, mkoutny@suse.com,
natalie.vock@gmx.de, mhocko@kernel.org, roman.gushchin@linux.dev,
shakeel.butt@linux.dev, muchun.song@linux.dev,
thomas.hellstrom@linux.intel.com,
dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
cgroups@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v8] cgroup/dmem: implement dmem.high soft limit with proactive reclaim
Date: Mon, 21 Sep 2026 08:13:47 -1000 [thread overview]
Message-ID: <7e555045eff532576b56daa4e023be1b@kernel.org> (raw)
In-Reply-To: <20260921-feature-dmem-high-v8-1-6371fa83d6c3@gmail.com>
Hello,
On Mon, Sep 21, 2026 at 03:02:48PM +0800, Qiliang Yuan wrote:
> The dmem cgroup v2 controller only provides a hard "max" limit, which
> fails allocations outright once a cgroup's device memory usage hits
> its quota. GPU-bound AI workloads need smoother over-subscription: a
> soft limit that applies backpressure through reclaim before the hard
> limit is hit.
That's not how max behaves. A max hit makes TTM evict and retry before the
allocation fails, and since 747c4bb450ad ("cgroup/dmem: Add reclaim
callback for lowering max below current usage") lowering max reclaims as
well. So the premise doesn't hold, and the patch doesn't show a concrete
case where max reclaim falls short and high would help. Without that,
there isn't enough justification for adding a new interface file.
Thanks.
--
tejun
prev parent reply other threads:[~2026-09-21 18:16 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-21 7:02 [PATCH v8] cgroup/dmem: implement dmem.high soft limit with proactive reclaim Qiliang Yuan
2026-09-21 18:13 ` Tejun Heo [this message]
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