Public bug reported:
After upgrading from 20.04 to 20.20 on my laptop, the machine became
extremely slow. After a days work I noticed that it never got any
faster, and the machine was a lot colder than usual. Running cat
/proc/cpuinfo and sudo cpupower frequency-info I noticed that the CPU
was locked to 400Mhz.
After some googling I found reports of people having trouble with CPU
frequency governors on kernel 5.8. I tried to add intel_pstate=active to
grub, but that didn't help.
My short term workaround is to choose the old 5.4 kernel from 20.04.
With this kernel everything is snappy again! Currently it's running at
3.2 Ghz with little load.
CPU info from /proc/cpuinfo (with kernel 5.4):
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 142
model name : Intel(R) Core(TM) i7-8665U CPU @ 1.90GHz
stepping : 12
microcode : 0xd6
cpu MHz : 4551.153
cache size : 8192 KB
physical id : 0
siblings : 8
core id : 0
cpu cores : 4
apicid : 0
initial apicid : 0
fpu : yes
fpu_exception : yes
cpuid level : 22
wp : yes
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 sse4_1 sse4_2 x2apic movbe popcnt
tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch
cpuid_fault epb invpcid_single ssbd ibrs ibpb stibp ibrs_enhanced tpr_shadow
vnmi flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms
invpcid mpx rdseed adx smap clflushopt intel_pt xsaveopt xsavec xgetbv1 xsaves
dtherm ida arat pln pts hwp hwp_notify hwp_act_window hwp_epp md_clear
flush_l1d arch_capabilities
bugs : spectre_v1 spectre_v2 spec_store_bypass swapgs taa
itlb_multihit srbds
bogomips : 4199.88
clflush size : 64
cache_alignment : 64
address sizes : 39 bits physical, 48 bits virtual
power management:
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1901406
Title:
Lenovo T490 extremely show with Ubuntu 20.20 running kernel 5.8
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