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Message-ID: <fe7188d5-d70c-0f4a-7998-99f2efcffdb6@collabora.com>
Date:   Thu, 23 Nov 2023 01:37:21 +0300
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Subject: Re: [PATCH v18 24/26] drm/virtio: Attach shmem BOs dynamically
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To:     Boris Brezillon <boris.brezillon@collabora.com>
Cc:     David Airlie <airlied@gmail.com>,
        Gerd Hoffmann <kraxel@redhat.com>,
        Gurchetan Singh <gurchetansingh@chromium.org>,
        Chia-I Wu <olvaffe@gmail.com>, Daniel Vetter <daniel@ffwll.ch>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>,
        Qiang Yu <yuq825@gmail.com>,
        Steven Price <steven.price@arm.com>,
        Emma Anholt <emma@anholt.net>, Melissa Wen <mwen@igalia.com>,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        kernel@collabora.com, virtualization@lists.linux-foundation.org
References: <20231029230205.93277-1-dmitry.osipenko@collabora.com>
 <20231029230205.93277-25-dmitry.osipenko@collabora.com>
 <20231113105745.7543e8dd@collabora.com>
From:   Dmitry Osipenko <dmitry.osipenko@collabora.com>
In-Reply-To: <20231113105745.7543e8dd@collabora.com>
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On 11/13/23 12:57, Boris Brezillon wrote:
> On Mon, 30 Oct 2023 02:02:03 +0300
> Dmitry Osipenko <dmitry.osipenko@collabora.com> wrote:
> 
>> Prepare for addition of memory shrinker support by attaching shmem pages
>> to host dynamically on first use. Previously the attachment vq command
>> wasn't fenced and there was no vq kick made in the BO creation code path,
>> hence the attachment already was happening dynamically, but implicitly.
>> Making attachment explicitly dynamic will allow to simplify and reuse more
>> code when shrinker will be added. The virtio_gpu_object_shmem_init() now
>> works under the held reservation lock, which will be important to have for
>> shrinker to avoid moving pages while they are in active use by the driver.
> Ah, this commit might actually help getting rid of the workaround
> introduced in "drm/shmem-helper: Add common memory shrinker".

Not really. The virtio_gpu_free_object() is unchanged, it's only
allocation that is being deferred and it's only done for a one BO type
(virtio-gpu has multiple BO types).

-- 
Best regards,
Dmitry