F #4089: add CPU limitations

src/vmm_mad/remotes/firecracker/deploy

@@ -54,6 +54,8 @@ end
 
 # Start VNC (only started if necessary)
 microvm.vnc('start')
+# Set cpu.shares (only if configured)
+microvm.set_cpu_limit
 
 # Set deploy_id
 puts "one-#{vm_id}"

src/vmm_mad/remotes/firecracker/firecrackerrc

@@ -58,6 +58,11 @@
 #
 # Timeout to wait a cgroup to be empty after shutdown/cancel a microVM
 :cgroup_delete_timeout: 60
+#
+# If true the cpu.shares will be set acording to the VM CPU value if false the
+# cpu.shares is left by default which means that all the resources are shared
+# equally acrros the VMs
+:cgroup_cpu_shares: true
 
 ################################################################################
 # NUMA placement Options

src/vmm_mad/remotes/lib/firecracker/microvm.rb

@@ -148,6 +148,18 @@ class MicroVM
     rescue Errno::ENOENT # rubocop:disable Lint/SuppressedException
     end
 
+    def cpu_shares(cpu)
+        # default value for cpu.shares
+        default_value = 1024
+
+        shares_val = (cpu * default_value).round
+
+        # The value specified in the cpu.shares file must be 2 or higher.
+        shares_val = 2 if shares_val < 2
+
+        shares_val
+    end
+
     #---------------------------------------------------------------------------
     # VNC
     #---------------------------------------------------------------------------
@@ -253,4 +265,14 @@ class MicroVM
     # rubocop:enable Naming/AccessorMethodName
     # rubocop:enable Layout/LineLength
 
+    def set_cpu_limit
+        return unless @one.fcrc[:cgroup_cpu_shares]
+
+        shares_location = "#{@one.fcrc[:cgroup_location]}/cpu/" \
+                          "firecracker/one-#{@one.vm_id}/cpu.shares"
+
+        cmd = "echo #{cpu_shares(@one.get_cpu)} > #{shares_location}"
+        `echo "AAA#{Command.execute_once(cmd, false)}" > /tmp/a`
+    end
+
 end

src/vmm_mad/remotes/lib/firecracker/opennebula_vm.rb

@@ -99,6 +99,10 @@ class OpenNebulaVM
         @vm_name && !@vm_name.include?('one-')
     end
 
+    def get_cpu
+        Float(@xml['//TEMPLATE/CPU'])
+    end
+
     # Returns a Hash representing the LXC configuration for this OpenNebulaVM
     def to_fc
         fc = {}
@@ -127,9 +131,10 @@ class OpenNebulaVM
     end
 
     #---------------------------------------------------------------------------
-    # Container Attribute Mapping
+    # MicroVM Attribute Mapping
     #---------------------------------------------------------------------------
-    # Creates a dictionary for Firecracker containing $MEMORY RAM allocated
+    # Creates a dictionary for Firecracker containing vm information
+
     def boot_source(hash)
         hash['kernel_image_path'] = 'kernel'
         hash['boot_args'] = @boot_args