Arch Linux

gcb

Member

Registered: 2014-02-12

Posts: 212

amd_pmc negative active time?

I can't find much info about amd_pmc, or even if this is used anywhere besides kernel development (I'm guessing yes, since it is included in my very basic arch install)

But while investigating a weird crash (which left nothing in the logs) I've seen this oddity:

# cd /sys/kernel/debug/amd_pmc/
# tail *
==> amd_pmc_idlemask <==
SMU idlemask : 0x8fdb1e15

==> s0ix_stats <==
=== S0ix statistics ===
S0ix Entry Time: 0
S0ix Exit Time: 0
Residency Time: 0

==> smu_fw_info <==
Time (in us) to resume from S0i3: -2926336059608043518

=== Active time (in us) ===
DISPLAY  : 8312726498156633196
VDD      : 1972629942519215054
ACP      : -622705002038864448
VCN      : 2546809748688213580
DF       : 7736266020596898860
USB3_0   : -4656972610723700832
USB3_1   : -1314608698638241149

How can time be negative?

cpu is AMD Ryzen 5 PRO 6650U

gcb

Member

Registered: 2014-02-12

Posts: 212

Re: amd_pmc negative active time?

guess it's just bad values from never having slept to measure the delays. doesn't look good, if those are used anywhere, but good news is that sleeping do set them as expected.

* sleep and wake *

# tail * 
==> amd_pmc_idlemask <==
SMU idlemask : 0x8cdb1e15

==> s0ix_stats <==
=== S0ix statistics ===
S0ix Entry Time: 99900066675
S0ix Exit Time: 100962736111
Residency Time: 22138946

==> smu_fw_info <==
Time (in us) to resume from S0i3: 400794

=== Active time (in us) ===
DISPLAY  : 0
VDD      : 0
ACP      : 0
VCN      : 0
DF       : 0
USB3_0   : 0
USB3_1   : 0