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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?r2maS3Shs0MLZw6uNg7Lvk5InQQgY2WSUEfhCnQxXX1Q4O0A/ic2P9wbDuqf?= =?us-ascii?Q?p/fTBupyHbpNzlSOkmAoaqCPn9OJgnJ6THD0zRcot4e1Pi9JfMvllxvWAOoS?= =?us-ascii?Q?nQbHsOhZX6U7TRfs08hZV+CmTpvLHFMRjQeqO/PfHfidYlepOUraNBgYWs27?= =?us-ascii?Q?5OF+OKAKPh0gijtKkXq43Os6gyleQDDW7EP1E8+zjdzeulzYY42d1gV6jPP8?= =?us-ascii?Q?0M8LUUqIQyzD/YjcYQ4zADKzAJadENfl/F+kaLmLmZyiAhkQim70pCUsEQxb?= =?us-ascii?Q?h3k+DOUl+cyk6Ymv46n/88O6rE12pGomDmjzJX/r6gbkLTrH/s7PUk8hgo8y?= =?us-ascii?Q?htE2+Psh4LZTvRm90VOy8/qptmJX23HihAk/V8CdIBWj4F4B98iRN551imUk?= =?us-ascii?Q?ZEzmcpOe37rRNPhPbdB9ZDOaJCk0kHwUvSMQkJ3Q0L6Pq/E0BoYM8lFSo3C4?= =?us-ascii?Q?iDK9rOOEu9NM4SNTUBh+X/a1zY6WwnGpKhz6a1RKpO/qfdMLcNXNVQWPE+Tz?= =?us-ascii?Q?RprCrNDFVu+FsZGglUb7ekYw16xKICyYBHz1kf6wGiVwDA/lkSUwJFGrXX6F?= =?us-ascii?Q?UkRcxJ6oZl1QjF8+vIuVVI5GsfBtWK6MR5EsekzmhIMbhL20NDDxuZkbShnF?= =?us-ascii?Q?6uK21Pgk3/o9dg1KFfw6aI9Gu5xFuDlldCMHg976TWRu+CT+os1C9m3bfhhZ?= =?us-ascii?Q?GwDvQUIf1ct60+93QIJ59H87jLq9PcT5zcb4fp2D6N4MD3AlktGMqrZkimhx?= =?us-ascii?Q?LuHaWWm0kGVbbdV8ZtmRBfp3d/BgFTjBdKIjT9OVTuR7hCq3eHomPOhNu/wd?= =?us-ascii?Q?kFAWu0vQpfC+r/BDn5RX13D5QbN3rTWKPPxnBXE6ePDBM2V8kJtR8HTt7FtQ?= =?us-ascii?Q?/ZMtIuMI0TbFDk60iI5VZwrtNhf3y5DqQTlgX24MO5x/XBAYYhCRFs0hOvl8?= =?us-ascii?Q?uflCRn4hP+rYzqje03RhknabFxx6UBEyAAjBjM5198SbhmIxhRil5KlERvg1?= =?us-ascii?Q?4SgMpgJEB1k9c5UQF+oGDg09yTFiZJHDvJrwMwFexaBWYvYCCT6c6d8A1XU7?= =?us-ascii?Q?6xdfMLelInkhMsSN2M5BlwPwWAgiqtzZbpL7qvnIUEwuuEMKtE/rkwfJaydk?= =?us-ascii?Q?Axy7LF9QdngxZmC18C6OJkKagELLYF9dTyIjY2bZF4BVZQysVAvZc19FYM2p?= =?us-ascii?Q?KGua+dTLUzn92T7q5EAb2Nt1Us9KhTTm+i6PbiTx2J4+9rwFUgiPCu+AUelh?= =?us-ascii?Q?Ji6bJXP5PLAb4VZEIOpqqLmci/PfAv1HD9uwgjjsTCoZ4izEvo71ZE8I4JYB?= =?us-ascii?Q?KGrbDsboukE2/lc0bQEXmLG0OsiE2JdzpJhLTQ6n917zCE0vr4rI6v23+e8U?= =?us-ascii?Q?pt7+Unrba3udF5Kvmpq52h8QjDapaqrzkbCjBMZWyfbXdOwrPtvRTJ7hTrbs?= =?us-ascii?Q?pY38+39WKjes6uAx6za+ogiuMNmOwHfb8mpXVFmesMlemEhMNPXxPlTz8L45?= =?us-ascii?Q?aKIowludQyz08dGD9kcA++o+m0oHAcfCsHIG4OfsSmnN6B5nqx77WaOmJy6T?= =?us-ascii?Q?wabEU5nbELgh1g3FbO1uaaHWtxyFFenpQkAU/su1ZgDRW8foShgcuspXAOz4?= =?us-ascii?Q?NyLtutku6ibgVWFSMGG2XaZ7DFfU5UgZauILMxHe/GX2JRdQSJnthukn7qIS?= =?us-ascii?Q?mcjeLNRwH881q1TcVkXwyJX2febTK2xGZY5E7A6WTdw0bfqavLLBoafYU8RE?= =?us-ascii?Q?TOyV6Zs7kIkL+0chLwGZdK4W8IOziY5ZG3Vzv9IJtl3/LEH4Xsks?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: d440eb62-3baf-41e8-2555-08df401af491 X-MS-Exchange-CrossTenant-AuthSource: LV3PR12MB9356.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 Nov 2026 17:41:02.8088 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: /wj4HFocGFDKEzZAhIOVfiJwPfEyzOA+Qlmj1R2Te7PRiZqdfTnv+yB4U42KUlX1SUdbVk9wwLeP2C+3w8BSRg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH1PPF351A22FF6 On Tue, Nov 10, 2026 at 02:45:58PM +0530, Shrikanth Hegde wrote: > Hi, > > On 11/10/26 8:45 AM, Maxim Kuvyrkov wrote: > > > On Nov 2, 2026, at 08:21, Yury Norov wrote: > > > > > > The preferred CPU mask currently lets the steal governor reduce vCPU > > > demand when physical CPUs are contended. This series adds manual control, > > > opening more use cases. > > > > > > For example, setting CPUs aside for selected fair tasks at runtime while > > > steering other fair tasks toward the remaining CPUs. > > > > Hi Yury, > > > > I've been trying to do this with crutches in user-space for a long time. Thanks for implementing this in the kernel, and with a convenient user interface. > > > > > > > > A user can mark a CPU non-preferred and pin a workload to it. Fair tasks > > > whose affinity includes preferred CPUs are steered away, while tasks > > > whose allowed CPUs contain no preferred CPU can still run there. The CPU > > > stays online, task affinity is preserved, and the selection can be > > > reversed without rebooting: > > > > > > # rmmod steal_governor > > > # echo 0 > /sys/devices/system/cpu/cpu3/preferred > > > # taskset -c 3 ./my_workload > > > # echo 1 > /sys/devices/system/cpu/cpu3/preferred > > > > My use-case (being a compiler optimization engineer) is to pin benchmarks to specific cores, and stop the system from using those cores even when the cores are idle. This prevents L1/L2 cache pollution and makes performance numbers more stable. > > > > Do you change it when running workload based on any signal/event? or you set it before starting it? > > If it is set before starting, you might as well offline the CPUs to achieve the same. I assume you are > managing the preferred CPUs manually with write interface. You can do the same for online state. > (Though it takes a longer) How that? I tried, and offlining destroys the affinity, as it should: # taskset -c 3 sh -c 'while :; do :; done' & [1] 380 # taskset -pc "$pid" pid 380's current affinity list: 3 # echo 0 >/sys/devices/system/cpu/cpu3/online [ 115.767634] process 380 (sh) no longer affine to cpu3 [ 115.772881] smpboot: CPU 3 is now offline taskset -pc 380 pid 380's current affinity list: 0-2,4-7 Did you mean something else, maybe?