Dear Linux folks,
On the Intel Kaby Lake laptop Dell XPS 13 9360,
`/sys/kernel/debug/pmc_core/slp_s0_residency_usec` does stay 0 even
after a s2idle suspend/resume cycle.
$ sudo dmesg
[…]
[ 0.000000] DMI: Dell Inc. XPS 13 9360/0596KF, BIOS 2.21.0
06/02/2022
[…]
[10176.745124] PM: suspend entry (s2idle)
[10176.757275] Filesystems sync: 0.012 seconds
[10176.769118] Freezing user space processes
[10176.771693] Freezing user space processes completed (elapsed
0.002 seconds)
[10176.771710] OOM killer disabled.
[10176.771714] Freezing remaining freezable tasks
[10176.773487] Freezing remaining freezable tasks completed
(elapsed 0.001 seconds)
[10176.773504] printk: Suspending console(s) (use
no_console_suspend to debug)
[10176.948337] ACPI: EC: interrupt blocked
[10176.951016] intel_pch_thermal 0000:00:14.2: CPU-PCH is cool [48C]
[10181.281827] ACPI: EC: interrupt unblocked
$ sudo more /sys/kernel/debug/pmc_core/slp_s0_residency_usec
0
Is that expected?
Kind regards,
Paul
PS: Some system details:
```
$ LANG= lspci -nn
00:00.0 Host bridge [0600]: Intel Corporation Xeon E3-1200 v6/7th Gen
Core Processor Host Bridge/DRAM Registers [8086:5904] (rev 02)
00:02.0 VGA compatible controller [0300]: Intel Corporation HD Graphics
620 [8086:5916] (rev 02)
00:04.0 Signal processing controller [1180]: Intel Corporation Xeon
E3-1200 v5/E3-1500 v5/6th Gen Core Processor Thermal Subsystem
[8086:1903] (rev 02)
00:14.0 USB controller [0c03]: Intel Corporation Sunrise Point-LP USB
3.0 xHCI Controller [8086:9d2f] (rev 21)
00:14.2 Signal processing controller [1180]: Intel Corporation Sunrise
Point-LP Thermal subsystem [8086:9d31] (rev 21)
00:15.0 Signal processing controller [1180]: Intel Corporation Sunrise
Point-LP Serial IO I2C Controller #0 [8086:9d60] (rev 21)
00:15.1 Signal processing controller [1180]: Intel Corporation Sunrise
Point-LP Serial IO I2C Controller #1 [8086:9d61] (rev 21)
00:16.0 Communication controller [0780]: Intel Corporation Sunrise
Point-LP CSME HECI #1 [8086:9d3a] (rev 21)
00:1c.0 PCI bridge [0604]: Intel Corporation Sunrise Point-LP PCI
Express Root Port #1 [8086:9d10] (rev f1)
00:1c.4 PCI bridge [0604]: Intel Corporation Sunrise Point-LP PCI
Express Root Port #5 [8086:9d14] (rev f1)
00:1d.0 PCI bridge [0604]: Intel Corporation Sunrise Point-LP PCI
Express Root Port #9 [8086:9d18] (rev f1)
00:1f.0 ISA bridge [0601]: Intel Corporation Sunrise Point-LP LPC
Controller [8086:9d58] (rev 21)
00:1f.2 Memory controller [0580]: Intel Corporation Sunrise Point-LP PMC
[8086:9d21] (rev 21)
00:1f.3 Audio device [0403]: Intel Corporation Sunrise Point-LP HD Audio
[8086:9d71] (rev 21)
00:1f.4 SMBus [0c05]: Intel Corporation Sunrise Point-LP SMBus
[8086:9d23] (rev 21)
01:00.0 PCI bridge [0604]: Intel Corporation DSL6340 Thunderbolt 3
Bridge [Alpine Ridge 2C 2015] [8086:1576]
02:00.0 PCI bridge [0604]: Intel Corporation DSL6340 Thunderbolt 3
Bridge [Alpine Ridge 2C 2015] [8086:1576]
02:01.0 PCI bridge [0604]: Intel Corporation DSL6340 Thunderbolt 3
Bridge [Alpine Ridge 2C 2015] [8086:1576]
02:02.0 PCI bridge [0604]: Intel Corporation DSL6340 Thunderbolt 3
Bridge [Alpine Ridge 2C 2015] [8086:1576]
39:00.0 USB controller [0c03]: Intel Corporation DSL6340 USB 3.1
Controller [Alpine Ridge] [8086:15b5]
3a:00.0 Network controller [0280]: Qualcomm Atheros QCA6174 802.11ac
Wireless Network Adapter [168c:003e] (rev 32)
3b:00.0 Non-Volatile memory controller [0108]: SK hynix PC300 NVMe Solid
State Drive 512GB [1c5c:1284]
$ LANG= lscpu
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Address sizes: 39 bits physical, 48 bits virtual
Byte Order: Little Endian
CPU(s): 4
On-line CPU(s) list: 0-3
Vendor ID: GenuineIntel
Model name: Intel(R) Core(TM) i7-7500U CPU @ 2.70GHz
CPU family: 6
Model: 142
Thread(s) per core: 2
Core(s) per socket: 2
Socket(s): 1
Stepping: 9
CPU(s) scaling MHz: 14%
CPU max MHz: 3500.0000
CPU min MHz: 400.0000
BogoMIPS: 5799.77
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 sy
scall 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 est tm2
ssse3 sdbg fma c
x16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe
popcnt tsc_dead
line_timer aes xsave avx f16c rdrand lahf_lm
abm 3dnowprefetc
h cpuid_fault epb ssbd ibrs ibpb stibp
tpr_shadow flexpriorit
y ept vpid ept_ad fsgsbase tsc_adjust sgx
bmi1 avx2 smep bmi2
erms invpcid mpx rdseed adx smap clflushopt
intel_pt xsaveop
t xsavec xgetbv1 xsaves dtherm ida arat pln
pts hwp hwp_notif
y hwp_act_window hwp_epp vnmi md_clear
flush_l1d arch_capabil
ities
Virtualization features:
Virtualization: VT-x
Caches (sum of all):
L1d: 64 KiB (2 instances)
L1i: 64 KiB (2 instances)
L2: 512 KiB (2 instances)
L3: 4 MiB (1 instance)
NUMA:
NUMA node(s): 1
NUMA node0 CPU(s): 0-3
Vulnerabilities:
Gather data sampling: Vulnerable
Itlb multihit: KVM: Mitigation: VMX disabled
L1tf: Mitigation; PTE Inversion; VMX vulnerable
Mds: Vulnerable; SMT vulnerable
Meltdown: Vulnerable
Mmio stale data: Vulnerable
Reg file data sampling: Not affected
Retbleed: Vulnerable
Spec rstack overflow: Not affected
Spec store bypass: Vulnerable
Spectre v1: Vulnerable: __user pointer sanitization and
usercopy barriers
only; no swapgs barriers
Spectre v2: Vulnerable; IBPB: disabled; STIBP: disabled;
PBRSB-eIBRS: Not
affected; BHI: Not affected
Srbds: Vulnerable
Tsx async abort: Not affected
```
