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On 10/15/26 09:16, Reinette Chatre wrote: > Hi Babu, > > On 10/1/26 8:10 AM, Babu Moger wrote: >> When memory bandwidth associated with a CLOSID is aggressively throttled, >> and a task with that CLOSID moves into kernel mode, the kernel operations >> are also aggressively throttled. This can stall forward progress and >> eventually degrade overall system performance. >> >> AMD hardware supports a feature Privilege Level Zero Association (PLZA), >> which allows the CPU's CLOSID and/or RMID association to be changed during >> the transition from user mode to kernel mode. This allows the kernel to run >> using a different CLOSID and/or RMID than user space, which can improve >> system performance and/or allow kernel work to be monitored separately. >> >> Note that PLZA feature associates CLOSID and/or RMID to kernel work, and >> therefore influences resource allocation and/or monitoring for all >> resources, not only memory bandwidth. >> >> The feature is detected via CPUID_Fn80000020_EBX_x00 [Bit 9]: Privilege >> Level Zero Association (PLZA). >> >> The PLZA feature details are documented in [1] available from [2]. >> >> [1] AMD64 Zen6 Platform Quality of Service (PQOS) Extensions: >> Publication # 69193 Revision: 1.00, Issue Date: March 2026 >> >> Signed-off-by: Babu Moger >> Acked-by: Borislav Petkov (AMD) >> Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537 # [2] >> --- > > Reviewed-by: Reinette Chatre > Thanks Babu