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Thread-Topic: How about increasing max_cpus for q35 ? 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micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-sCZBTL7ZId2JwSdqO91p" MIME-Version: 1.0 X-OriginatorOrg: suse.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: PAXPR04MB8366.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: babafc85-e491-413e-4c68-08dac2575b6b X-MS-Exchange-CrossTenant-originalarrivaltime: 09 Nov 2022 13:36:07.7579 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: f7a17af6-1c5c-4a36-aa8b-f5be247aa4ba X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: 65U+IGHiqkymdbdunare4OiaLTuy8w+fBsuuCPnSuFRohpJWmd2h9Ngv8XBQVLXJPJ6+hCC+zqSGbzx8XtOvKg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: AS4PR04MB9481 Received-SPF: pass client-ip=2a01:111:f400:fe0c::62c; envelope-from=dfaggioli@suse.com; helo=EUR04-DB3-obe.outbound.protection.outlook.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org --=-sCZBTL7ZId2JwSdqO91p Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hello, Sorry for the potentially naive question, but I'm not clear what the process would be if, say, I'd like to raise the number of maximum CPUs a q35 VM can have. So, right now we have: void pc_q35_2_7_machine_options(MachineClass *m) { ... m->max_cpus =3D 255; } And: void pc_q35_machine_options(MachineClass *m) { ... m->max_cpus =3D 288; } Focusing on the latter, it comes from this commit: https://gitlab.com/qemu-project/qemu/-/commit/00d0f9fd6602a27b204f672ef5bc8= e69736c7ff1 =20 pc: q35: Bump max_cpus to 288 Along with it for machine versions 2.7 and older keep it at 255. So, it was 255 and is now 288. This seems to me to be there since QEMU 2.8.0. Now, as far as I understand, KVM can handle 1024, at least since this commit (and a couple of other related ones): https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?= id=3D074c82c8f7cf8a46c3b81965f122599e3a133450 "kvm: x86: Increase MAX_VCPUS to 1024" Which basically does: -#define KVM_MAX_VCPUS 288 +#define KVM_MAX_VCPUS 1024 And it's included in kernels >=3D 5.15. So, what's the correct way of bumping up the limit again? Just changing that assignment in pc_q35_machine_options() ? Or do we want a new version of the machine type or something like that? Thanks and Regards --=20 Dario Faggioli, Ph.D http://about.me/dario.faggioli Virtualization Software Engineer SUSE Labs, SUSE https://www.suse.com/ ------------------------------------------------------------------- <> (Raistlin Majere) --=-sCZBTL7ZId2JwSdqO91p Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEES5ssOj3Vhr0WPnOLFkJ4iaW4c+4FAmNrrMYACgkQFkJ4iaW4 c+5xow/9H4UPoIvpmnd1wOqa8FODevTP2cmECdlA1iTeO+cqSTlnFSUSKQwMw2CK yvvmi+wh9u8ToyXcHgr0O8BBl+xle+y7cbRCDUAMZtfj9rzS69ywDLcwyYO49a9k qvbkHNi7mQF1tFNbtmJU5OYpKBVt11bY4+nfOCKXbEtBD5TIbMEAYNO6EEqPrhTw 8REUzbFcpX+AZceD+5MIgE5BHtodrEWuTooGJEZ2I2xs+ZXJ/9lP+dE1IHqxdBji x5jrMldu8AX3aAg9nyraFgEiZk/AjD+KlewmzshFqGPTL352KiKncRG8oAHLgTXQ VJUqtYVM9t0jLrIBU+5LKh2URPqSqTZvmSl6iee91HTVl9AtJXaPeSG3JaGxr8Zs asV/xhEEnynXWRyWXDTARXc0U9nc9LFXCxJaop7b25M/PWTttaDBIV7uV2lnMOBN fvCq+Pf/C/+YFk16jqX5uZYj3tne+5TJme2vW/R8tkf3xVdUQsDbBVZ2tNIqlhKo DYtWLkgoZzF9gyn4+6DI5+JAHUSWAO8t1nwuuaTf+bh7/Rzf/c4eYX5lSAQehhjI p1W4cTamVAniL5G00xRm6d2pVJ2bwxKctDt72wc3va+Vekoe7Gx4nJIKLBR2lfUC 3oKrUXX4p2/pBuc7wJShA5woQhbgzZI+SPBVf8JbYCQhR9NmKoQ= =l9fL -----END PGP SIGNATURE----- --=-sCZBTL7ZId2JwSdqO91p--