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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 21 Jan 2026 21:08:51.6374 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 59186790-d1e4-47af-962b-08de59314745 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=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: DS3PEPF000099DB.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA1PR12MB7639 This patch series adds support for Global Bandwidth Enforcement (GLBE), Global Slow Bandwidth Enforcement (GLSBE) and Priviledge Level Zero Association (PLZA) in the x86 architecture's fs/resctrl subsystem. The changes include modifications to the resctrl filesystem to allow users to configure GLBE settings and associate CPUs and tasks with a separate CLOS when executiing in CPL0. The feature documentation is not yet publicly available, but it is expected to be released in the next few weeks. In the meantime, a brief description of the features is provided below. Sharing this series as an RFC to gather initial feedback. Comments are welcome. Global Bandwidth Enforcement (GLBE) AMD Global Bandwidth Enforcement (GLBE) provides a mechanism for software to specify bandwidth limits for groups of threads that span multiple QOoS Domains. This collection of QOS Domains is referred to as the GLBE Control Domain. The GLBE ceiling is a bandwidth ceiling for L3 External Bandwidth competitively shared between all threads in a COS (Class of Service) across all QOS Domains within the GLBE Control Domain. This complements L3BE L3 External Bandwidth Enforcement (L3BE) which provides L3 eExternal Bandwidth control on a per QOS Domain granularity. Global Slow Bandwidth Enforcement (GLSBE) AMD PQoS Global Slow Bandwidth Enforcement (GLSBE) provides a mechanism for software to specify bandwidth limits for groups of threads that span multiple QOS Domains. GLSBE operates within the same GLBE Control Domains defined by GLBE. The GLSBE ceiling is a bandwidth ceiling for L3 External Bandwidth to Slow Memory competitively shared between all threads in a COS in all QOS Domains within the GLBE Control Domain. This complements L3SMBE which provides Slow Memory bandwidth control on a per QOS Domain granularity. Privilege Level Zero Association (PLZA) Privilege Level Zero Association (PLZA) allows the hardware to automatically associate execution in Privilege Level Zero (CPL=0) with a specific COS (Class of Service) and/or RMID (Resource Monitoring Identifier). The QoS feature set already has a mechanism to associate execution on each logical processor with an RMID or COS. PLZA allows the system to override this per-thread association for a thread that is executing with CPL=0. The patches are based on top of commit (v6.19-rc5) Commit 0f61b1860cc3 (tag: v6.19-rc5, tip/tip/urgent) Linux 6.19-rc5 Changes include: - Introduction of a new max_bandwidth file for each resctrl resource to expose the maximum supported bandwidth. - Addition of new schemata GMB and GSMBA interfaces for configuring GLBE and GSLBE parameters. - Modifications to associate resctrl groups with PLZA. - Documentation updates to describe the new functionality. Interface Changes: 1. A new max_bandwidth file has been added under each resource type directory (for example, /sys/fs/resctrl/info/GMB/max_bandwidth) to report the maximum bandwidth supported by the resource. 2. New resource types, GMB and GSMBA, have been introduced and are exposed through the schemata interface: # cat /sys/fs/resctrl/schemata GSMBA:0=4096;1=4096 SMBA:0=8192;1=8192 GMB:0=4096;1=4096 MB:0=8192;1=8192 L3:0=ffff;1=ffff 3. A new plza_capable file has been added under each resource type directory (for example, /sys/fs/resctrl/info/GMB/plza_capable) to indicate whether the resource supports the PLZA feature. 4. A new plza control file has been added to each resctrl group (for example, /sys/fs/resctrl/plza) to enable or disable PLZA association for the group. Writing 1 enables PLZA for the group, while writing 0 disables it. Babu Moger (1): x86,fs/resctrl: Add support for Global Bandwidth Enforcement (GLBE) Documentation/admin-guide/kernel-parameters.txt | 2 +- arch/x86/include/asm/cpufeatures.h | 2 +- arch/x86/kernel/cpu/resctrl/core.c | 2 ++ arch/x86/kernel/cpu/scattered.c | 1 + 4 files changed, 5 insertions(+), 2 deletions(-) -- 2.34.1