Bug 216833

Summary:	TSC as timecounter makes system lag on Core 2 generation hardware with EARLY_AP_STARTUP
Product:	Base System	Reporter:	Jia-Shiun Li <jiashiun>
Component:	kern	Assignee:	freebsd-bugs (Nobody) <bugs>
Status:	Closed FIXED
Severity:	Affects Some People	Keywords:	regression
Priority:	---
Version:	CURRENT
Hardware:	amd64
OS:	Any

Description Jia-Shiun Li 2017-02-05 19:42:20 UTC

Originally discussed on freebsd-current@
https://lists.freebsd.org/pipermail/freebsd-current/2017-January/064419.html

Since r310177 enablement of EARLY_AP_STARTUP, system time lags behind on Intel Core 2 generation hardware (family 6 model 17). It happens to me on Intel Pentium T4200 and Core 2 E7400. Larry Rosenman (ler@) also confirmed it happening on Xeon E5410.

Workaround:
- Disable EARLY_AP_STARTUP, or
- sysctl kern.timecounter.hardware=HPET

Comment 1 Jia-Shiun Li 2017-02-25 08:40:05 UTC

fixed in base r314211.