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Message-ID: <9b23e9d4-7c7a-a74f-3a6b-939a4a469c2b@amazon.com>
Date: Wed, 30 Nov 2022 08:10:43 -0800
From: "Bhatnagar, Rishabh" <risbhat@...zon.com>
To: <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<srinivas.pandruvada@...ux.intel.com>, <lenb@...nel.org>
CC: <surajjs@...zon.com>
Subject: Using nr_cpus breaks no_turbo setting of pstate driver
"Having some issue with my mails failing to deliver. So trying once
again after disabling HTML."
Hi Srinivas/Len,
I have been doing some testing on m5zn.metal AWS instances which
provides 48 vcpus and 192GB memory.
Test includes loading all cpus with maximum capacity (using stress) and
observing the frequency after enabling and disabling turbo frequencies.
Intel_pstate is enabled with hwp.
lscpu output for reference:
*# lscpu*
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 48
On-line CPU(s) list: 0-47
Thread(s) per core: 2
Core(s) per socket: 12
Socket(s): 2
NUMA node(s): 2
Vendor ID: GenuineIntel
CPU family: 6
Model: 85
Model name: Intel(R) Xeon(R) Platinum 8252C CPU @ 3.80GHz
Stepping: 7
CPU MHz: 3800.000
CPU max MHz: 4500.0000
CPU min MHz: 1200.0000
BogoMIPS: 7600.00
Virtualization: VT-x
L1d cache: 32K
L1i cache: 32K
L2 cache: 1024K
L3 cache: 25344K
NUMA node0 CPU(s): 0-11,24-35
NUMA node1 CPU(s): 12-23,36-47
Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr
pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe
syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts
rep_good nopl xtopology nonstop_tsc cpuid aperfmperf 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 rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb cat_l3 cdp_l3
invpcid_single intel_ppin ssbd mba ibrs ibpb stibp ibrs_enhanced
tpr_shadow vnmi flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1
avx2 smep bmi2 erms invpcid cqm mpx rdt_a avx512f avx512dq rdseed adx
smap clflushopt clwb intel_pt avx512cd avx512bw avx512vl xsaveopt xsavec
xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local dtherm
ida arat pln pts hwp hwp_act_window hwp_epp hwp_pkg_req pku ospke
avx512_vnni md_clear flush_l1d arch_capabilities
When testing with all cpus online I don't see any issue. CPUs reach
turbo frequency when intel_pstate/no_turbo is disabled and stay below
turbo frequencies when no_turbo is enabled as expected.
However, issue occurs when I boot with nr_cpus argument specifying less
than 48 cpus. e.g. cmdline:
*/# cat /proc/cmdline/*/
/mmio_stale_data=off mds=off tsx=off tsx_async_abort=off
intel_idle.max_cstate=0
BOOT_IMAGE=/boot/vmlinuz-5.10.154-119.671.amzn2.x86_64
root=UUID=d8605abb-d6cd-4a46-a657-b6bd206da2ab ro console=tty0
console=ttyS0,115200n8 net.ifnames=0 biosdevname=0
nvme_core.io_timeout=4294967295 rd.emergency=poweroff
rd.shell=0*nr_cpus=24 intel_idle.max_cstate=1 processor.max_cstate=1*
# echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo
# turbostat
^CPackage Core CPU Avg_MHz Busy% Bzy_MHz TSC_MHz IRQ
SMI POLL C1 POLL% C1% CPU%c1 CPU%c6 CoreTmp PkgTmp
Pkg%pc2 Pkg%pc6 PkgWatt RAMWatt PKG_% RAM_%
- - - 4370 99.76 4381 3800 6374 0
0 0 0.00 0.00 0.24 0.00 96 96 0.00
0.00 479.79 69.20 0.00 0.00
0 0 0 4292 99.93 4295 3800 266 0
0 0 0.00 0.00 0.07 0.00 88 96 0.00
0.00 239.89 33.62 0.00 0.00
0 2 1 4292 99.92 4295 3800 270 0
0 0 0.00 0.00 0.08 0.00 92
0 4 2 4292 99.92 4295 3800 264 0
0 0 0.00 0.00 0.08 0.00 92
0 8 3 4292 99.93 4295 3800 268 0
0 0 0.00 0.00 0.07 0.00 90
0 9 4 4292 99.93 4295 3800 264 0
0 0 0.00 0.00 0.07 0.00 91
0 10 5 4292 99.92 4295 3800 264 0
0 0 0.00 0.00 0.08 0.00 92
0 11 6 4292 99.92 4295 3800 265 0
0 0 0.00 0.00 0.08 0.00 96
0 17 7 4292 99.93 4295 3800 266 0
0 0 0.00 0.00 0.07 0.00 91
0 19 8 4292 99.93 4295 3800 266 0
0 0 0.00 0.00 0.07 0.00 91
0 25 9 4292 99.92 4295 3800 264 0
0 0 0.00 0.00 0.08 0.00 91
0 26 10 4292 99.92 4295 3800 264 0
0 0 0.00 0.00 0.08 0.00 93
0 27 11 4292 99.92 4295 3800 264 0
0 0 0.00 0.00 0.08 0.00 94
1 1 12 4449 99.61 4466 3800 264 0
0 0 0.00 0.00 0.39 0.00 80 88 0.00
0.00 239.90 35.58 0.00 0.00
1 2 13 4448 99.60 4466 3800 264 0
0 0 0.00 0.00 0.40 0.00 86
1 3 14 4449 99.61 4466 3800 267 0
0 0 0.00 0.00 0.39 0.00 81
1 8 15 4449 99.61 4466 3800 264 0
0 0 0.00 0.00 0.39 0.00 79
1 9 16 4448 99.60 4466 3800 264 0
0 0 0.00 0.00 0.40 0.00 79
1 10 17 4449 99.61 4466 3800 264 0
0 0 0.00 0.00 0.39 0.00 83
1 17 18 4448 99.60 4466 3800 264 0
0 0 0.00 0.00 0.40 0.00 82
1 18 19 4449 99.61 4466 3800 281 0
0 0 0.00 0.00 0.39 0.00 80
1 19 20 4449 99.61 4466 3800 264 0
0 0 0.00 0.00 0.39 0.00 83
1 20 21 4448 99.59 4466 3800 264 0
0 0 0.00 0.00 0.41 0.00 83
1 25 22 4448 99.60 4466 3800 264 0
0 0 0.00 0.00 0.40 0.00 81
1 27 23 4448 99.59 4466 3800 265 0
0 0 0.00 0.00 0.41 0.00 88
/
/
As part of the turbostat output I could see that pstate driver is
setting the hints correctly in MSR_HWP_REQUEST. But somehow these limits
are not being honored by HWP logic.
cpu0: MSR_PM_ENABLE: 0x00000001 (HWP)
cpu0: MSR_HWP_CAPABILITIES: 0x070c262d (high 45 guar 38 eff 12 low 7)
*cpu0: MSR_HWP_REQUEST: 0x00002626 (min 38 max 38 des 0 epp 0x0 window
0x0 pkg 0x0)*
cpu0: MSR_HWP_REQUEST_PKG: 0x8000ff00 (min 0 max 255 des 0 epp 0x80
window 0x0)
cpu0: MSR_HWP_STATUS: 0x00000004 (No-Guaranteed_Perf_Change,
No-Excursion_Min)
I tried the same experiment after disabling hwp by
specifying*intel_pstate=no_hwp*in cmdline. In this case the pstate
driver seems to be selecting pstates correctly.
^CPackage Core CPU Avg_MHz Busy% Bzy_MHz TSC_MHz IRQ
SMI POLL C1 POLL% C1% CPU%c1 CPU%c6 CoreTmp PkgTmp
Pkg%pc2 Pkg%pc6 PkgWatt RAMWatt PKG_% RAM_%
- - - 3800 100.00 3800 3800 1646 0
0 0 0.00 0.00 0.00 0.00 85 85 0.00
0.00 328.38 62.14 0.00 0.00
0 0 0 3800 100.00 3800 3800 66 0
0 0 0.00 0.00 0.00 0.00 85 85 0.00
0.00 175.42 36.96 0.00 0.00
0 0 24 3800 100.00 3800 3800 70 0
0 0 0.00 0.00 0.00
0 1 1 3800 100.00 3800 3800 65 0
0 0 0.00 0.00 0.00 0.00 82
0 2 2 3800 100.00 3800 3800 67 0
0 0 0.00 0.00 0.00 0.00 84
0 3 3 3800 100.00 3800 3800 67 0
0 0 0.00 0.00 0.00 0.00 83
0 4 4 3800 100.00 3800 3800 68 0
0 0 0.00 0.00 0.00 0.00 85
0 8 5 3800 100.00 3800 3800 68 0
0 0 0.00 0.00 0.00 0.00 83
0 9 6 3800 100.00 3800 3800 65 0
0 0 0.00 0.00 0.00 0.00 85
0 10 7 3800 100.00 3800 3800 65 0
0 0 0.00 0.00 0.00 0.00 82
0 11 8 3800 100.00 3800 3800 65 0
0 0 0.00 0.00 0.00 0.00 84
0 17 9 3800 100.00 3800 3800 65 0
0 0 0.00 0.00 0.00 0.00 83
0 18 10 3800 100.00 3800 3800 65 0
0 0 0.00 0.00 0.00 0.00 83
0 27 11 3800 100.00 3800 3800 65 0
0 0 0.00 0.00 0.00 0.00 85
1 0 12 3800 100.00 3800 3800 65 0
0 0 0.00 0.00 0.00 0.00 66 68 0.00
0.00 152.95 25.18 0.00 0.00
1 2 13 3800 100.00 3800 3800 65 0
0 0 0.00 0.00 0.00 0.00 65
1 4 14 3800 100.00 3800 3800 65 0
0 0 0.00 0.00 0.00 0.00 68
1 8 15 3800 100.00 3800 3800 65 0
0 0 0.00 0.00 0.00 0.00 63
1 9 16 3800 100.00 3800 3800 65 0
0 0 0.00 0.00 0.00 0.00 65
1 10 17 3800 100.00 3800 3800 65 0
0 0 0.00 0.00 0.00 0.00 64
1 17 18 3800 100.00 3800 3800 66 0
0 0 0.00 0.00 0.00 0.00 63
1 18 19 3800 100.00 3800 3800 66 0
0 0 0.00 0.00 0.00 0.00 63
1 19 20 3800 100.00 3800 3800 65 0
0 0 0.00 0.00 0.00 0.00 63
1 20 21 3800 100.00 3800 3800 66 0
0 0 0.00 0.00 0.00 0.00 66
1 25 22 3800 100.00 3800 3800 65 0
0 0 0.00 0.00 0.00 0.00 64
1 27 23 3800 100.00 3800 3800 67 0
0 0 0.00 0.00 0.00 0.00 67
[root@...172-31-36-94 ec2-user]# cat
/sys/devices/system/cpu/intel_pstate/no_turbo
1
Thanks,
Rishabh
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