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X86 timing: Difference between revisions
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* [[ACPI]] counter | * [[ACPI]] counter | ||
* LAPIC counter | * LAPIC counter | ||
* HPET | * HPET. Unprivileged programmability is limited by <tt>/proc/sys/dev/hpet/max-user-freq</tt> (in Hz): | ||
<pre>[recombinator](1) $ cat /proc/sys/dev/hpet/max-user-freq | |||
64 | |||
[recombinator](0) $ </pre> | |||
* TSC since Pentium | * TSC since Pentium | ||
* RTC ([http://fxr.watson.org/fxr/source/Documentation/rtc.txt?v=linux-2.6 Linux docs]) | * RTC ([http://fxr.watson.org/fxr/source/Documentation/rtc.txt?v=linux-2.6 Linux docs]) | ||
Revision as of 07:46, 27 June 2009
- PIT -- Programmable Interval Timer (eg Intel 8253)
- ACPI counter
- LAPIC counter
- HPET. Unprivileged programmability is limited by /proc/sys/dev/hpet/max-user-freq (in Hz):
[recombinator](1) $ cat /proc/sys/dev/hpet/max-user-freq 64 [recombinator](0) $
- TSC since Pentium
- RTC (Linux docs)
- ACPI standardized the cmos-rtc type, extending the Motorola MC146818 (CONFIG_RTC_DRV_CMOS at the LKDD)
[recombinator](0) $ cat /proc/driver/rtc rtc_time : 07:43:30 rtc_date : 2009-06-27 alrm_time : **:00:00 alrm_date : ****-**-** alarm_IRQ : no alrm_pending : no 24hr : yes periodic_IRQ : no update_IRQ : no HPET_emulated : yes DST_enable : no periodic_freq : 1024 batt_status : okay [recombinator](0) $
- Linux clocksources vs clockevents
