Installation guide

Virtual machine timer management with libvirt
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Table 24.2. name attribute values
Value Description
platform The master virtual time source which may be
used to drive the policy of other time sources.
pit Programmable Interval Timer - a timer with
periodic interrupts.
rtc Real Time Clock - a continuously running timer
with periodic interrupts.
hpet High Precision Event Timer - multiple timers
with periodic interrupts.
tsc Time Stamp Counter - counts the number of
ticks since reset, no interrupts.
•
wallclock
Specifies whether the wallclock should track host or guest time. Only valid for a name value of
platform or rtc.
Table 24.3. wallclock attribute values
Value Description
host RTC wallclock always tracks host time.
guest RTC wallclock always tracks guest time.
•
tickpolicy
The policy used to pass ticks on to the guest.
Table 24.4. tickpolicy attribute values
Value Description
none Continue to deliver at normal rate (i.e. ticks are
delayed).
catchup Deliver at a higher rate to catch up.
merge Ticks merged into one single tick.
discard All missed ticks are discarded.
•
frequency
Used to set a fixed frequency, measured in Hz. This attribute is only relevant for a name value of
tsc. All other timers operate at a fixed frequency (pit, rtc), or at a frequency fully controlled by
the guest (hpet).
•
mode
Determines how the time source is exposed to the guest. This attribute is only relevant for a name
value of tsc. All other timers are always emulated.
Table 24.5. mode attribute values
Value Description
auto Native if safe, otherwise emulated.
native Always native.
emulate Always emulate.