...

• /sys/module/kvm/parameters/halt_poll_ns = 0
  /sys/kernel/ktimer_lockless_check = 1
  /sys/kernel/mm/ksm/run = 2

• Kernel parameters :
  isolcpus=managed_irq,domain,{isolated_cores}
  intel_pstate=disable
  nosoftlockup
  tsc=reliable
  nohz=on
  nohz_full={isolated_cores}
  rcu_nocbs={isolated_cores}
  irqaffinity={non_isolated_cores}
  processor.max_cstate=1
  intel_idle.max_cstate=1
  cpufreq.default_governor=performance
  rcu_nocb_poll

• kernel thread priorities :
  group.ksoftirqd=0:f:2:*:^\[ksoftirqd
  group.ktimers=0:f:2:*:^\[ktimers
  group.rcuc=0:f:4:*:^\[rcuc
  group.rcub=0:f:4:*:^\[rcub
  group.ktimersoftd=0:f:3:*:^\[ktimersoftd

• configures irqbalance with isolated_cores list

• configures workqueue with isolated_cores list

• kernel.hung_task_timeout_secs = 600
  kernel.nmi_watchdog = 0
  kernel.sched_rt_runtime_us = -1
  vm.stat_interval = 10
  kernel.timer_migration = 0

VM configuration

The official documentation on the XML format of libvirt is here.

Resources

On the XML configuration of a virtual machine, the resource can be specified to know which slice should be used (more details here). So, the virtual machine will only have acces to the CPU associated with the slice.

Possible values:

• /machine/nort
• /machine/rt

Example, for a virtual machine with the real-time:

<resource>
	<partition>/machine/rt</partition>
</resource>

CPU tunning

In the project, this element will be used to limite the virtual machine (more details here).

• The emulatorpin element specifies which of host physical CPUs the emulator, a subset of a domain not including vCPU or iothreads will be pinned to.
• The vcpupin element specifies which of host's physical CPUs the domain vCPU will be pinned to. It's used to reserved one or more CPUs for a critical virtual machine. So, it's important not use this CPU on another VM.
• The vcpusched element specifies the scheduler type for a particular vCPU. A priority can be setting. In the project, all values greats than 10, it's for the host; equals to 10, it's for the RCU and less than 10, it's to set the priority of the RT vCPU among themselves.