Re: [PATCH v8] cgroup/dmem: implement dmem.high soft limit with proactive reclaim

[Tejun Heo]

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