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From: "Thomas Hellström" <thomas.hellstrom@linux.intel.com>
To: Tejun Heo <tj@kernel.org>
Cc: intel-xe@lists.freedesktop.org,
	"Natalie Vock" <natalie.vock@gmx.de>,
	"Johannes Weiner" <hannes@cmpxchg.org>,
	"Michal Koutný" <mkoutny@suse.com>,
	cgroups@vger.kernel.org, "Huang Rui" <ray.huang@amd.com>,
	"Matthew Brost" <matthew.brost@intel.com>,
	"Matthew Auld" <matthew.auld@intel.com>,
	"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
	"Maxime Ripard" <mripard@kernel.org>,
	"Thomas Zimmermann" <tzimmermann@suse.de>,
	"Simona Vetter" <simona@ffwll.ch>,
	"David Airlie" <airlied@gmail.com>,
	"Christian König" <christian.koenig@amd.com>,
	"Thadeu Lima de Souza Cascardo" <cascardo@igalia.com>,
	"Alex Deucher" <alexander.deucher@amd.com>,
	"Rodrigo Vivi" <rodrigo.vivi@intel.com>,
	dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v7 3/6] cgroup/dmem: Add reclaim callback for lowering max below current usage
Date: Tue, 07 Jul 2026 09:20:35 +0200	[thread overview]
Message-ID: <67ffc76ee6d1aa4e9ef5f4c393304914359eeaab.camel@linux.intel.com> (raw)
In-Reply-To: <akwBFlw8MwhrwsRu@slm.duckdns.org>

Hi,

On Mon, 2026-07-06 at 09:25 -1000, Tejun Heo wrote:
> Hello,
> 
> On Fri, Jul 03, 2026 at 03:05:38PM +0200, Thomas Hellström wrote:
> > Also honor O_NONBLOCK so that if that flag is set during the
> > max value write, no reclaim is initiated. The idea is to avoid
> > charging the reclaim cost to the writer of the max value.
> 
> Is this really necessary? I'm not necessarily against it but this is
> trivial
> to work around from userspace and feels like a gratuitous addition.
> What's
> the use case?

This was something that was added at the request of Maarten. The idea
is to mimic the memcg behaviour. For memcg, the use-case was to avoid
having the reclaim cost (I assume in terms of cpu time) land on the
next allocator instead of the process writing the new max value.

I think there are more details in the memcg commit history, but the
presence here is solely to mimic memcg WRT this.

Thanks,
Thomas 

> 
> Thanks.

  reply	other threads:[~2026-07-07  7:20 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-03 13:05 [PATCH v7 0/6] Add reclaim to the dmem cgroup controller Thomas Hellström
2026-07-03 13:05 ` [PATCH v7 1/6] drm/amdgpu: Fix init ordering in amdgpu_vram_mgr_init() Thomas Hellström
2026-07-03 13:08   ` Christian König
2026-07-03 13:11     ` Thomas Hellström
2026-07-03 13:05 ` [PATCH v7 2/6] cgroup/dmem: Introduce struct dmem_cgroup_init for region initialization Thomas Hellström
2026-07-03 13:05 ` [PATCH v7 3/6] cgroup/dmem: Add reclaim callback for lowering max below current usage Thomas Hellström
2026-07-06 19:25   ` Tejun Heo
2026-07-07  7:20     ` Thomas Hellström [this message]
2026-07-07 10:01     ` Maarten Lankhorst
2026-07-03 13:05 ` [PATCH v7 4/6] drm/ttm: Hook up a cgroup-aware reclaim callback for the dmem controller Thomas Hellström
2026-07-03 13:05 ` [PATCH v7 5/6] drm/xe: Wire up dmem cgroup reclaim for VRAM manager Thomas Hellström
2026-07-03 13:05 ` [PATCH v7 6/6] drm/amdgpu: " Thomas Hellström
2026-07-03 14:37 ` [PATCH v7 0/6] Add reclaim to the dmem cgroup controller Thadeu Lima de Souza Cascardo

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