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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Jan 2026 02:56:35.8992 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: df3e64e2-7e95-42d0-9058-08de5961db54 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb08.amd.com] X-MS-Exchange-CrossTenant-AuthSource: SN1PEPF0002BA4F.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA0PR12MB4413 Hello Peter, On 1/21/2026 9:46 PM, Peter Zijlstra wrote: > On Tue, Jan 20, 2026 at 11:32:38AM +0000, K Prateek Nayak wrote: > >> "sd->shared" is only allocated for the topmost SD_SHARE_LLC domain and >> the topology layer uses the sched domain degeneration path to pass the >> reference to the final "sd_llc" domain. > > I'm fairly sure we've had patches that introduced it for other levels at > various times, but clearly none of those ever made it. > > Anyway, a quick peek seems to suggest it is still easy to extend. > > >> include/linux/sched/topology.h | 1 - >> kernel/sched/fair.c | 62 +++++++----------- >> kernel/sched/sched.h | 2 +- >> kernel/sched/topology.c | 111 ++++++++++++++++++++++----------- >> 4 files changed, 101 insertions(+), 75 deletions(-) > > Is this really worth the extra lines though? The larger plan was to move the "nohz.idle_cpus" tracking into the sched_domain_shared instance which will bloat these allocations. Instead of (#CPUs x #topology_levels) surplus, most of which will get reclaimed at the end anyways, we'll only have #CPUs worth of allocations now. -- Thanks and Regards, Prateek