Class: Distem::Algorithm::CPU::Gov

Inherits:
Distem::Algorithm show all
Defined in:
lib/distem/algorithm/cpu/gov.rb

Overview

Algorithm based on CPU throttling methods (see en.wikipedia.org/wiki/Dynamic_frequency_scaling). A core is changing his frequency periodatically between two values to reach the wished one i.e. if our physical core can change it's frequency to 1.5GHz, 2.0GHz and 2.5GHz and we want it to be set at 2.3GHz, this algorithm will make the core work 40% of the time at 2GHz and 60% at 2.5GHz.

Instance Method Summary (collapse)

Constructor Details

- (Gov) initialize

Create a new Gov object



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# File 'lib/distem/algorithm/cpu/gov.rb', line 9

def initialize()
  super()
  @ext = nil
end

Instance Method Details

- (Object) apply(vnode)

Apply the algorithm on a resource (virtual node)

Attributes

  • vnode The VNode object



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# File 'lib/distem/algorithm/cpu/gov.rb', line 18

def apply(vnode)
  super(vnode)
  cores = []
  freqmax = nil
  lfreq = nil
  hfreq = nil
  wfreq = nil # wished frequency
  ratio = nil
  if vnode.vcpu and vnode.vcpu.vcores
    #check available frequencies table
    pcores = vnode.host.cpu.get_allocated_cores(vnode)
    cores = pcores.collect{ |core| core.physicalid.to_i }
    vcore = vnode.vcpu.vcores[vnode.vcpu.vcores.keys[0]]
    freqs = vcore.pcore.frequencies
    freqs.sort
    freqmax = vcore.pcore.frequency
    wfreq = vcore.frequency.to_i
    # if the wished frequency is one of the cpu possible frequency
    if freqs.index(wfreq)
      lfreq = wfreq
      hfreq = wfreq
      ratio = 1.0
    else
      hfreq = freqs.select{|val| val >= wfreq}[0]
      if hfreq == freqs[0]
        lfreq = 0 
      else
        lfreq = freqs[freqs.index(hfreq) - 1]
      end
    end
  end

  unless cores.empty?
    @ext = CPUExtension::CPUGov.new(
      cores,freqmax,"#{Node::Admin::PATH_CGROUP}/#{vnode.name}"
    )
    ratio = (wfreq.to_f - hfreq) / (lfreq - hfreq) unless ratio
    @ext.run(lfreq.to_i,hfreq.to_i,ratio.to_f)
  end
end

- (Object) undo(vnode)

Undo the algorithm on a resource (virtual node)

Attributes

  • vnode The VNode object



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# File 'lib/distem/algorithm/cpu/gov.rb', line 63

def undo(vnode)
  super(vnode)
  if @ext
    @ext.stop
    @ext = nil
  end
end