Re: [PATCH 0/2] arch/x86: Set L2 Cache ID on AMD processors

[K Prateek Nayak <kprateek.nayak@amd.com>]

Hello Oleksandr,

Thank you for testing the series.

On 4/13/2023 6:47 PM, Oleksandr Natalenko wrote:
> Hello.
> 
> On pondělí 10. dubna 2023 18:35:25 CEST K Prateek Nayak wrote:
>> commit 66558b730f253 ("sched: Add cluster scheduler level for x86")
>> defined cluster on x86 as the set of threads sharing the same L2 cache.
>> cluster_id on x86, maps to the l2c_id which currently only Intel
>> processors set.
>>
>> This series sets the l2c_id on AMD processors with X86_FEATURE_TOPOEXT,
>> using the extended APIC ID and the "Cache Properties (L2)" CPUID
>> (0x8000001D EAX). On AMD processors without X86_FEATURE_TOPOEXT, current
>> behavior will continue.
>>
>> Following are the changes in value reported by
>> "/sys/devices/system/cpu/cpuX/topology/cluster_id" on a 2P Milan system
>> (2 x 64C/128T) where L2 is per-core level and SMT sibling of CPU (X) is
>> CPU ((X + 128) % 256).
>>
>> - tip:x86/core
>>
>>   $ for i in {0..255}; do\
>>       echo -n "CPU$i cluster_id: ";\
>>       cat /sys/devices/system/cpu/cpu$i/topology/cluster_id;\
>>     done;
>>
>>     CPU0 cluster_id: 65535
>>     CPU1 cluster_id: 65535
>>     CPU2 cluster_id: 65535
>>     CPU3 cluster_id: 65535
>>     CPU4 cluster_id: 65535
>>     ...
>>     CPU254 cluster_id: 65535
>>     CPU255 cluster_id: 65535
>>
>> - tip:x86/core + this series
>>
>>   $ for i in {0..255}; do\
>>       echo -n "CPU$i cluster_id: ";\
>>       cat /sys/devices/system/cpu/cpu$i/topology/cluster_id;\
>>     done;
>>
>>     CPU0 cluster_id: 0
>>     CPU1 cluster_id: 1
>>     CPU2 cluster_id: 2
>>     CPU3 cluster_id: 3
>>     CPU4 cluster_id: 4
>>     CPU5 cluster_id: 5
>>     CPU6 cluster_id: 6
>>     CPU7 cluster_id: 7
>>     CPU8 cluster_id: 8
>>     ...
>>     CPU126 cluster_id: 126
>>     CPU127 cluster_id: 127
>>     CPU128 cluster_id: 0
>>     CPU129 cluster_id: 1
>>     CPU130 cluster_id: 2
>>     CPU131 cluster_id: 3
>>     CPU132 cluster_id: 4
>>     CPU133 cluster_id: 5
>>     CPU134 cluster_id: 6
>>     CPU135 cluster_id: 7
>>     CPU136 cluster_id: 8
>>     ...
>>     CPU254 cluster_id: 126
>>     CPU255 cluster_id: 127
>>
>> Note: Hygon, theoretically, should be able to set the l2c_id using the
>> same cacheinfo_amd_init_l2c_id() function being added in Patch 1. Since
>> I do not have access to a Hygon machine to verify my theory, ccing Hygon
>> maintainer Pu Wen <puwen@hygon.cn> for l2c_id enablement on Hygon.
>>
>> The series also adds documentation for clusters on x86 platforms and
>> applies cleanly on top of tip:x86/core at commit ce3ba2af9695
>> ("x86: Suppress KMSAN reports in arch_within_stack_frames()")
>>
>> ---
>> K Prateek Nayak (2):
>>   arch/x86: Set L2 Cache ID on AMD and Hygon processors
>>   x86/Documentation: Add documentation about cluster
>>
>>  Documentation/x86/topology.rst   | 31 +++++++++++++++++++++
>>  arch/x86/include/asm/cacheinfo.h |  1 +
>>  arch/x86/kernel/cpu/amd.c        |  1 +
>>  arch/x86/kernel/cpu/cacheinfo.c  | 47 ++++++++++++++++++++++++++++++++
>>  arch/x86/kernel/cpu/hygon.c      |  1 +
>>  5 files changed, 81 insertions(+)
> 
> Having the following CPU:
> 
> ```
> Architecture:            x86_64
> CPU op-mode(s):        32-bit, 64-bit
> Address sizes:         48 bits physical, 48 bits virtual
> Byte Order:            Little Endian
> CPU(s):                  32
> On-line CPU(s) list:   0-31
> Vendor ID:               AuthenticAMD
> Model name:            AMD Ryzen 9 5950X 16-Core Processor
> CPU family:          25
> Model:               33
> Thread(s) per core:  2
> Core(s) per socket:  16
> Socket(s):           1
> Stepping:            2
> Frequency boost:     enabled
> CPU(s) scaling MHz:  37%
> CPU max MHz:         5084,0000
> CPU min MHz:         550,0000
> BogoMIPS:            6789,07
> Flags:               fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_
> tsc rep_good nopl nonstop_tsc cpuid extd_apicid aperfmperf rapl pni pclmulqdq monitor ssse3 fma cx16 sse4_1 sse4_2 x2apic movbe popcnt aes xsave avx f16c r
> drand lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs skinit wdt tce topoext perfctr_core perfctr_nb bpext perfctr_l
> lc mwaitx cpb cat_l3 cdp_l3 hw_pstate ssbd mba ibrs ibpb stibp vmmcall fsgsbase bmi1 avx2 smep bmi2 erms invpcid cqm rdt_a rdseed adx smap clflushopt clwb
> sha_ni xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local clzero irperf xsaveerptr rdpru wbnoinvd arat npt lbrv svm_lock nrip
> _save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold avic v_vmsave_vmload vgif v_spec_ctrl umip pku ospke vaes vpclmulqdq rdpid ove
> rflow_recov succor smca fsrm
> Virtualization features:
> Virtualization:        AMD-V
> Caches (sum of all):
> L1d:                   512 KiB (16 instances)
> L1i:                   512 KiB (16 instances)
> L2:                    8 MiB (16 instances)
> L3:                    64 MiB (2 instances)
> NUMA:
> NUMA node(s):          1
> NUMA node0 CPU(s):     0-31
> Vulnerabilities:
> Itlb multihit:         Not affected
> L1tf:                  Not affected
> Mds:                   Not affected
> Meltdown:              Not affected
> Mmio stale data:       Not affected
> Retbleed:              Not affected
> Spec store bypass:     Mitigation; Speculative Store Bypass disabled via prctl
> Spectre v1:            Mitigation; usercopy/swapgs barriers and __user pointer sanitization
> Spectre v2:            Mitigation; Retpolines, IBPB conditional, IBRS_FW, STIBP always-on, RSB filling, PBRSB-eIBRS Not affected
> Srbds:                 Not affected
> Tsx async abort:       Not affected
> ```
> 
> Without the series:
> 
> ```
> /sys/devices/system/cpu/cpu0/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu1/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu2/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu3/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu4/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu5/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu6/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu7/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu8/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu9/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu10/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu11/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu12/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu13/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu14/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu15/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu16/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu17/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu18/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu19/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu20/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu21/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu22/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu23/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu24/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu25/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu26/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu27/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu28/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu29/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu30/topology/cluster_id:65535
> /sys/devices/system/cpu/cpu31/topology/cluster_id:65535
> ```
> 
> With the series:
> 
> ```
> /sys/devices/system/cpu/cpu0/topology/cluster_id:0
> /sys/devices/system/cpu/cpu1/topology/cluster_id:1
> /sys/devices/system/cpu/cpu2/topology/cluster_id:2
> /sys/devices/system/cpu/cpu3/topology/cluster_id:3
> /sys/devices/system/cpu/cpu4/topology/cluster_id:4
> /sys/devices/system/cpu/cpu5/topology/cluster_id:5
> /sys/devices/system/cpu/cpu6/topology/cluster_id:6
> /sys/devices/system/cpu/cpu7/topology/cluster_id:7
> /sys/devices/system/cpu/cpu8/topology/cluster_id:8
> /sys/devices/system/cpu/cpu9/topology/cluster_id:9
> /sys/devices/system/cpu/cpu10/topology/cluster_id:10
> /sys/devices/system/cpu/cpu11/topology/cluster_id:11
> /sys/devices/system/cpu/cpu12/topology/cluster_id:12
> /sys/devices/system/cpu/cpu13/topology/cluster_id:13
> /sys/devices/system/cpu/cpu14/topology/cluster_id:14
> /sys/devices/system/cpu/cpu15/topology/cluster_id:15
> /sys/devices/system/cpu/cpu16/topology/cluster_id:0
> /sys/devices/system/cpu/cpu17/topology/cluster_id:1
> /sys/devices/system/cpu/cpu18/topology/cluster_id:2
> /sys/devices/system/cpu/cpu19/topology/cluster_id:3
> /sys/devices/system/cpu/cpu20/topology/cluster_id:4
> /sys/devices/system/cpu/cpu21/topology/cluster_id:5
> /sys/devices/system/cpu/cpu22/topology/cluster_id:6
> /sys/devices/system/cpu/cpu23/topology/cluster_id:7
> /sys/devices/system/cpu/cpu24/topology/cluster_id:8
> /sys/devices/system/cpu/cpu25/topology/cluster_id:9
> /sys/devices/system/cpu/cpu26/topology/cluster_id:10
> /sys/devices/system/cpu/cpu27/topology/cluster_id:11
> /sys/devices/system/cpu/cpu28/topology/cluster_id:12
> /sys/devices/system/cpu/cpu29/topology/cluster_id:13
> /sys/devices/system/cpu/cpu30/topology/cluster_id:14
> /sys/devices/system/cpu/cpu31/topology/cluster_id:15
> ```
> 
> Hence,
> 
> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>

I've retained your tag in Patch 1 of v2
(https://lore.kernel.org/lkml/20230413172918.1500-2-kprateek.nayak@amd.com/)
since there are no functional changes for AMD in v2.

> 
> Thanks.
> 

--
Thanks and Regards,
Prateek