I'm seeing the same thing. Basically, any use of clock_gettime now
requires a syscall (isntead of using vsdo). The applications I'm running
do a lot of clock_gettime's, and basically cannot run performantly
anymore after this happens.
This machine is a:
System Information
Manufacturer: Alienware
Product Name: Alienware Aurora Ryzen Edition
Version: 1.0.1
cpu:
processor : 31
vendor_id : AuthenticAMD
cpu family : 23
model : 113
model name : AMD Ryzen 9 3950X 16-Core Processor
stepping : 0
microcode : 0x8701013
kernel:
4.15.0-121-generic #123-Ubuntu SMP Mon Oct 5 16:16:40 UTC 2020 x86_64 x86_64
x86_64 GNU/Linux
kernel log after resuming from sleep:
Oct 14 15:28:59 viable kernel: [ 3442.068452] Measured 70 cycles TSC warp
between CPUs, turning off TSC clock.
Oct 14 15:28:59 viable kernel: [ 3442.068455] tsc: Marking TSC unstable due to
check_tsc_sync_source failed
Oct 14 15:28:59 viable kernel: [ 3442.068472] TSC found unstable after boot,
most likely due to broken BIOS. Use 'tsc=unstable'.
Oct 14 15:28:59 viable kernel: [ 3442.068473] sched_clock: Marking unstable
(3442081459163, -14096408)<-(3442040805073, 27665648)
Oct 14 15:28:59 viable kernel: [ 3442.068582] cache: parent cpu1 should not be
sleeping
Oct 14 15:28:59 viable kernel: [ 3442.068845] CPU1 is up
Oct 14 15:28:59 viable kernel: [ 3442.067786] clocksource: Switched to
clocksource hpet
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https://bugs.launchpad.net/bugs/1821441
Title:
Clocksource changes from TSC to HPET after sleep. Kills performance.
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