X86 timing: Difference between revisions
flesh out data about the TSC, especially the new RDTSCP instruction |
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* PIT -- Programmable Interval Timer (eg [http://en.wikipedia.org/wiki/Intel_8253 Intel 8253]) | * PIT -- Programmable Interval Timer (eg [http://en.wikipedia.org/wiki/Intel_8253 Intel 8253]) | ||
* [[ACPI]] counter (PMTMR, Power Management Timer) | * [[ACPI]] counter (PMTMR, Power Management Timer) | ||
* LAPIC counter | * [[LAPIC]] counter | ||
* HPET. Unprivileged programmability is limited by <tt>/proc/sys/dev/hpet/max-user-freq</tt> (in Hz): | * 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 | <pre>[recombinator](1) $ cat /proc/sys/dev/hpet/max-user-freq | ||
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* Multiple RTC's might exist in a machine, thus Linux's "RTC Class" | * Multiple RTC's might exist in a machine, thus Linux's "RTC Class" | ||
** Each RTC gets a device node (by default, <tt>/dev/rtc*</tt> | ** Each RTC gets a device node (by default, <tt>/dev/rtc*</tt> | ||
** If [sysfs] is enabled, each gets an entry at <tt>/sys/class/rtc/*/</tt>: | ** If [[sysfs]] is enabled, each gets an entry at <tt>/sys/class/rtc/*/</tt>: | ||
<pre>[recombinator](0) $ ls /sys/class/rtc/rtc0/ | <pre>[recombinator](0) $ ls /sys/class/rtc/rtc0/ | ||
date device name since_epoch time wakealarm | date device name since_epoch time wakealarm | ||