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Fri, 3 Apr 2026 17:24:09 -0400 (EDT) Date: Fri, 3 Apr 2026 23:24:07 +0200 From: Marek =?utf-8?Q?Marczykowski-G=C3=B3recki?= To: Teddy Astie Cc: Val Packett , Demi Marie Obenour , Xen developer discussion , dri-devel@lists.freedesktop.org, linux-mm@kvack.org, Ariadne Conill Subject: Re: Why memory lending is needed for GPU acceleration Message-ID: References: <84462c4b-7813-4ad1-aeb2-862ae4f3a627@gmail.com> <0bbf0349-1006-485f-a2db-6c8b795b4242@invisiblethingslab.com> <1de15ce0-9f7e-4253-80a7-ecd94caa4325@vates.tech> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="4Ae0y7aT9vuqArIi" Content-Disposition: inline In-Reply-To: <1de15ce0-9f7e-4253-80a7-ecd94caa4325@vates.tech> X-Rspamd-Server: rspam12 X-Stat-Signature: axbdbqhhwzpj8cwnntp1i4ftdxwagd17 X-Rspamd-Queue-Id: 799811A000A X-Rspam-User: X-HE-Tag: 1775251453-234416 X-HE-Meta: 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 f5n4lSXK 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: --4Ae0y7aT9vuqArIi Content-Type: text/plain; protected-headers=v1; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Date: Fri, 3 Apr 2026 23:24:07 +0200 From: Marek =?utf-8?Q?Marczykowski-G=C3=B3recki?= To: Teddy Astie Cc: Val Packett , Demi Marie Obenour , Xen developer discussion , dri-devel@lists.freedesktop.org, linux-mm@kvack.org, Ariadne Conill Subject: Re: Why memory lending is needed for GPU acceleration On Tue, Mar 31, 2026 at 09:42:22AM +0000, Teddy Astie wrote: > XEN_GNTDEV_DMABUF has been designed for GPU use-cases, and more > precisely for paravirtualizing a display. The only issue I would have > with it is that grants are not scalable for GPU 3D use cases (with > hundreds of MB to share). FWIW we do use grants for graphics buffers already - window composition buffers specifically. We do run xen with extra options for that: gnttab_max_frames=3D2048 gnttab_max_maptrack_frames=3D4096 And similarly, on domU side: echo 1073741824 > /sys/module/xen_gntalloc/parameters/limit --=20 Best Regards, Marek Marczykowski-G=C3=B3recki Invisible Things Lab --4Ae0y7aT9vuqArIi Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhrpukzGPukRmQqkK24/THMrX1ywFAmnQL/gACgkQ24/THMrX 1yxbGQf+OgsupCAnm7yeXU50i8UAUbaCxLl6LTgomVWE8BqqFLLzbd1uZRBaxgwi 08KM6UwaNDnWYrJjTzzuVajjgvb364NRxaCcDQMU1gg9QaScwe0rvqNXjTCyyZIZ KcGYITuyNobu6TEOlxjMZCYe09hjh5Tv6YIAjNytG/v4Wj0BeLd6dpU3y/K79rsz k5Q2KuSQNJBm0DrX1xHtYDI34Ecs8kMi+QNmTxBNirLjkzswlCpewSvOONNsy8Ff 8k+hGeZuhbRQMidzb/toBQpk5p82359YvtUwGWz6rn/YnryTk6+3x3Vr1octMvgz 5SPKxfVNDvikjgpYpZpWowiX1sDLHw== =Aya7 -----END PGP SIGNATURE----- --4Ae0y7aT9vuqArIi--