Difference between revisions of "Kernel configuration"

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(New page: == ACPI sleep == It is a bit tricky to make ACPI sleep and OpenVZ work together. ACPI sleep is enabled by <code>ACPI_SLEEP</code> kernel option. The following dependencies are declared i...)
 
(added intro, mention cpulimits/cpuunits)
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This article summarises various kernel configuration issues.
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== ACPI sleep ==
 
== ACPI sleep ==
  
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On non-SMP machine, you may disable <code>SMP</code>, this will resolve the conflict.
 
On non-SMP machine, you may disable <code>SMP</code>, this will resolve the conflict.
  
If you have SMP machine, you can only disable <code>FAIRSCHED</code> and <code>SCHED_VCPU</code>. This will loose isolation between VEs (scheduling will be performed per-task, not per-VE), but it is acceptable solution if your VEs are trusted (and it's hard to imagine untrusted VEs on notebook ;)
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If you have SMP machine, you can only disable <code>FAIRSCHED</code> and <code>SCHED_VCPU</code>. This will loose some isolation between VEs (CPU scheduling will be performed per-task, not per-VE, and <code>cpuunits</code> and <code>cpulimit</code> settings will not take effect), but it is acceptable solution if your VEs are trusted (and it's hard to imagine untrusted VEs on a notebook ;)
  
 
[[Category:Kernel]]
 
[[Category:Kernel]]
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[[Category:HOWTO]]

Revision as of 05:40, 22 February 2007

This article summarises various kernel configuration issues.

ACPI sleep

It is a bit tricky to make ACPI sleep and OpenVZ work together.

ACPI sleep is enabled by ACPI_SLEEP kernel option. The following dependencies are declared in kernel configs:

ACPI_SLEEP depends on X86 && (!SMP || SUSPEND_SMP)
SUSPEND_SMP depends on HOTPLUG_CPU && X86 && PM
FAIRSCHED depends on SCHED_VCPU

And SCHED_VCPU is incompatible with HOTPLUG_CPU:

./kernel/cpu.c:#error "CONFIG_HOTPLUG_CPU isn't supported with CONFIG_SCHED_VCPU"

On non-SMP machine, you may disable SMP, this will resolve the conflict.

If you have SMP machine, you can only disable FAIRSCHED and SCHED_VCPU. This will loose some isolation between VEs (CPU scheduling will be performed per-task, not per-VE, and cpuunits and cpulimit settings will not take effect), but it is acceptable solution if your VEs are trusted (and it's hard to imagine untrusted VEs on a notebook ;)