3 ms·
So, this is all about HPET _as it is used by Windows_, right? They talk about 'forced on in the OS', they mean Windows. Anyone know how the various PC timers ar
by brianolson 8y ago
So, this is all about HPET _as it is used by Windows_, right? They talk about 'forced on in the OS', they mean Windows. Anyone know how the various PC timers are used in Linux?
- paol 8y agoI think Linux will use HPET if the hardware makes it available. You can prevent that with "hpet=disable" in the kernel boot parameters.
- cesarb 8y agoYes, Linux will use the HPET if it's available, but it prefers the TSC when possible, which is the case in most modern CPUs. For instance, you will see the following in the kernel log: [ 0.062020] clocksource: Switched to clocksource hpet [...] [ 2.383237] clocksource: Switched to clocksource tsc Here, it started with the HPET, calibrated the TSC, and switched to it. There's no need to disable the HPET for it to chose something else as the best timing source.
- floatboth 8y agoAny reasonable OS should use TSC as the main timer. e.g. FreeBSD assigns a higher quality score to TSC: Timecounter "TSC-low" frequency 1500043470 Hz quality 1000 Timecounter "i8254" frequency 1193182 Hz quality 0 Timecounter "HPET" frequency 14318180 Hz quality 950 Timecounter "ACPI-fast" frequency 3579545 Hz quality 900