mba_MBps doesn't work on Xeon 6972P with AlmaLinux 9.6

[hiromasaw]

Hi,
I'm trying to use mba_MBps for memory bandwidth control, but mba_MBps won't become enabled.
What should I check?
Please let me know if any information is missing.

mount -t resctrl resctrl /sys/fs/resctrl -o mba_MBps

mount: /sys/fs/resctrl: wrong fs type, bad option, bad superblock on resctrl, missing codepage or helper program, or other error.

lscpu

Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Address sizes: 52 bits physical, 57 bits virtual
Byte Order: Little Endian
CPU(s): 192
On-line CPU(s) list: 0-191
Vendor ID: GenuineIntel
BIOS Vendor ID: Intel(R) Corporation
Model name: Intel(R) Xeon(R) 6972P
BIOS Model name: Intel(R) Xeon(R) 6972P
CPU family: 6
Model: 173
Thread(s) per core: 1
Core(s) per socket: 96
Socket(s): 2
Stepping: 1
BogoMIPS: 4800.00
Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmo
v pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe
syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon p
ebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf
tsc_known_freq pni pclmulqdq dtes64 monitor ds_cpl vmx smx
est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2
x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c r
drand lahf_lm abm 3dnowprefetch cpuid_fault epb cat_l3 cat_l
2 cdp_l3 intel_ppin cdp_l2 ssbd mba ibrs ibpb stibp ibrs_enh
anced tpr_shadow flexpriority ept vpid ept_ad fsgsbase tsc_a
djust bmi1 avx2 smep bmi2 erms invpcid cqm rdt_a avx512f avx
512dq rdseed adx smap avx512ifma clflushopt clwb intel_pt av
x512cd sha_ni avx512bw avx512vl xsaveopt xsavec xgetbv1 xsav
es cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local split_l
ock_detect avx_vnni avx512_bf16 wbnoinvd dtherm ida arat pln
pts hfi vnmi avx512vbmi umip pku ospke waitpkg avx512_vbmi2
gfni vaes vpclmulqdq avx512_vnni avx512_bitalg tme avx512_v
popcntdq la57 rdpid bus_lock_detect cldemote movdiri movdir6
4b enqcmd fsrm md_clear serialize tsxldtrk pconfig arch_lbr
ibt amx_bf16 avx512_fp16 amx_tile amx_int8 flush_l1d arch_ca
pabilities
Virtualization features:
Virtualization: VT-x
Caches (sum of all):
L1d: 9 MiB (192 instances)
L1i: 12 MiB (192 instances)
L2: 384 MiB (192 instances)
L3: 960 MiB (2 instances)
NUMA:
NUMA node(s): 6
NUMA node0 CPU(s): 0-31
NUMA node1 CPU(s): 32-63
NUMA node2 CPU(s): 64-95
NUMA node3 CPU(s): 96-127
NUMA node4 CPU(s): 128-159
NUMA node5 CPU(s): 160-191
Vulnerabilities:
Gather data sampling: Not affected
Indirect target selection: Not affected
Itlb multihit: Not affected
L1tf: Not affected
Mds: Not affected
Meltdown: Not affected
Mmio stale data: Not affected
Reg file data sampling: Not affected
Retbleed: Not affected
Spec rstack overflow: Not affected
Spec store bypass: Mitigation; Speculative Store Bypass disabled via prctl
Spectre v1: Mitigation; usercopy/swapgs barriers and __user pointer sani
tization
Spectre v2: Mitigation; Enhanced / Automatic IBRS; IBPB conditional; RSB
filling; PBRSB-eIBRS Not affected; BHI BHI_DIS_S
Srbds: Not affected
Tsx async abort: Not affected

uname -a

Linux gra01.local 5.14.0-570.58.1.el9_6.x86_64 #1 SMP PREEMPT_DYNAMIC Wed Oct 29 06:24:11 EDT 2025 x86_64 x86_64 x86_64 GNU/Linux

grep -i resctrl /boot/config-5.14.0-570.58.1.el9_6.x86_64

CONFIG_X86_CPU_RESCTRL=y
CONFIG_PROC_CPU_RESCTRL=y

Without -o mba_MBps, I can mount resctrl successfully.

mount -t resctrl resctrl /sys/fs/resctrl

mount | grep resctrl

resctrl on /sys/fs/resctrl type resctrl (rw,relatime)

/usr/local/bin/rdtset -t 'mba=20;cpu=0-191' -c 0-191 /bin/date

Fri Jan 16 03:23:34 PM JST 2026

/usr/local/bin/rdtset -t 'mba_max=2000;cpu=0-191' -c 0-191 /bin/date

Allocation: MBA CTRL requested but not enabled. Please enable MBA CTRL.
Requested configuration is not valid!
Allocation: Failed to configure allocation!

I'm using intel-cmt-cat v25.04 Apr 2025.

Best regards,
WATANABE