Installation guide

ManualsBrandsRed Hat ManualsComputer equipmentLINUX VIRTUAL SERVER 5.1 - ADMINISTRATION

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5.5 x86 with the para-virtualized clock Additional parameters are not required

5.5 x86 without the para-virtualized clock clocksource=acpi_pm lpj=n

5.4 AMD64/Intel 64 notsc

5.4 x86 clocksource=acpi_pm

5.3 AMD64/Intel 64 notsc

5.3 x86 clocksource=acpi_pm

4.8 AMD64/Intel 64 notsc

4.8 x86 clock=pmtmr

3.9 AMD64/Intel 64 Additional parameters are not required

3.9 x86 Additional parameters are not required

Red Hat En terp rise Lin u x versio n Ad d it io nal g u est kern el p aramet ers

Note

The lpj parameter requires a numeric value equal to the loops per jiffy value of the specific

CPU on which the guest virtual machine runs. If you do not know this value, do not set the lpj

parameter.

Warning

The divider kernel parameter was previously recommended for Red Hat Enterprise Linux 4

and 5 guest virtual machines that did not have high responsiveness requirements, or exist on

systems with high guest density. It is no longer recommended for use with guests running Red

Hat Enterprise Linux 4, or Red Hat Enterprise Linux 5 versions prior to version 5.8.

divider can improve throughput on Red Hat Enterprise Linux 5 versions equal to or later

than 5.8 by lowering the frequency of timer interrupts. For example, if HZ= 10 0 0, and divider

is set to 10 (that is, d i vi d er= 10 ), the number of timer interrupts per period changes from the

default value (1000) to 100 (the default value, 1000, divided by the divider value, 10).

BZ #698842 details a bug in the way that the divider parameter interacts with interrupt and

tick recording. This bug is fixed as of Red Hat Enterprise Linux 5.8. However, the divider

parameter can still cause kernel panic in guests using Red Hat Enterprise Linux 4, or Red Hat

Enterprise Linux 5 versions prior to version 5.8.

This parameter was not implemented in Red Hat Enterprise Linux 3, so this bug does not affect

Red Hat Enterprise Linux 3 guests.

Red Hat Enterprise Linux 6 does not have a fixed-frequency clock interrupt; it operates in

tickless mode and uses the timer dynamically as required. The divider parameter is therefore

not useful for Red Hat Enterprise Linux 6, and Red Hat Enterprise Linux 6 guests are not

affected by this bug.

14 .3. Using t he Real-T ime Clock wit h Windows Server 2003 and

Windows XP guest s

⁠Chapt er 1 4 . KVM guest t iming manag ement

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