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StevenNoonan
Paper Tape
Posts: 1
Registered: ‎02-08-2019
Location: US
Views: 592
Message 1 of 1

ThinkPad A485 TSC broken on BIOS 1.16

The ThinkPad A485 BIOS seems to be breaking TSC synchronization:

 

https://bugzilla.kernel.org/show_bug.cgi?id=202525

 

Basically, CPU0 has a TSC offset of about -1600ms from all the other CPUs. Since AMD CPUs do not support MSR_IA32_TSC_ADJUST, the Linux kernel isn't able to compensate for the delta and falls back to using clocksource=hpet (which is about 100x slower to read compared to the TSC). This will cause some serious performance problems for anything that reads a clocksource via clock_gettime/gettimeofday/ftime/etc.

 

Are there any Lenovo firmware engineers reading this forum?

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