1 .. SPDX-License-Identifier: BSD-3-Clause
2 Copyright(c) 2010-2014 Intel Corporation.
4 Virtual Machine Power Management Application
5 ============================================
7 Applications running in virtual environments have an abstract view of
8 the underlying hardware on the host. Specifically, applications cannot
9 see the binding of virtual components to physical hardware. When looking
10 at CPU resourcing, the pinning of Virtual CPUs (vCPUs) to Physical CPUs
11 (pCPUs) on the host is not apparent to an application and this pinning
12 may change over time. In addition, operating systems on Virtual Machines
13 (VMs) do not have the ability to govern their own power policy. The
14 Machine Specific Registers (MSRs) for enabling P-state transitions are
15 not exposed to the operating systems running on the VMs.
17 The solution demonstrated in this sample application shows an example of
18 how a DPDK application can indicate its processing requirements using
19 VM-local only information (vCPU/lcore, and so on) to a host resident VM
20 Power Manager. The VM Power Manager is responsible for:
22 - **Accepting requests for frequency changes for a vCPU**
23 - **Translating the vCPU to a pCPU using libvirt**
24 - **Performing the change in frequency**
26 This application demonstrates the following features:
28 - **The handling of VM application requests to change frequency.**
29 VM applications can request frequency changes for a vCPU. The VM
30 Power Management Application uses libvirt to translate that
31 virtual CPU (vCPU) request to a physical CPU (pCPU) request and
32 performs the frequency change.
34 - **The acceptance of power management policies from VM applications.**
35 A VM application can send a policy to the host application. The
36 policy contains rules that define the power management behaviour
37 of the VM. The host application then applies the rules of the
38 policy independent of the VM application. For example, the
39 policy can contain time-of-day information for busy/quiet
40 periods, and the host application can scale up/down the relevant
41 cores when required. See :ref:`sending_policy` for information on
42 setting policy values.
44 - **Out-of-band monitoring of workloads using core hardware event counters.**
45 The host application can manage power for an application by looking
46 at the event counters of the cores and taking action based on the
47 branch miss/hit ratio. See :ref:`enabling_out_of_band`.
49 **Note**: This functionality also applies in non-virtualised environments.
51 In addition to the ``librte_power`` library used on the host, the
52 application uses a special version of ``librte_power`` on each VM, which
53 directs frequency changes and policies to the host monitor rather than
54 the APCI ``cpufreq`` ``sysfs`` interface used on the host in non-virtualised
57 .. _figure_vm_power_mgr_highlevel:
59 .. figure:: img/vm_power_mgr_highlevel.*
63 In the above diagram, the DPDK Applications are shown running in
64 virtual machines, and the VM Power Monitor application is shown running
67 **DPDK VM Application**
69 - Reuse ``librte_power`` interface, but uses an implementation that
70 forwards frequency requests to the host using a ``virtio-serial`` channel
71 - Each lcore has exclusive access to a single channel
72 - Sample application reuses ``l3fwd_power``
73 - A CLI for changing frequency from within a VM is also included
77 - Accepts VM commands over ``virtio-serial`` endpoints, monitored
79 - Commands include the virtual core to be modified, using ``libvirt`` to get
80 the physical core mapping
81 - Uses ``librte_power`` to affect frequency changes using Linux userspace
82 power governor (``acpi_cpufreq`` OR ``intel_pstate`` driver)
83 - CLI: For adding VM channels to monitor, inspecting and changing channel
84 state, manually altering CPU frequency. Also allows for the changings
85 of vCPU to pCPU pinning
87 Sample Application Architecture Overview
88 ----------------------------------------
90 The VM power management solution employs ``qemu-kvm`` to provide
91 communications channels between the host and VMs in the form of a
92 ``virtio-serial`` connection that appears as a para-virtualised serial
93 device on a VM and can be configured to use various backends on the
94 host. For this example, the configuration of each ``virtio-serial`` endpoint
95 on the host as an ``AF_UNIX`` file socket, supporting poll/select and
96 ``epoll`` for event notification. In this example, each channel endpoint on
97 the host is monitored for ``EPOLLIN`` events using ``epoll``. Each channel
98 is specified as ``qemu-kvm`` arguments or as ``libvirt`` XML for each VM,
99 where each VM can have several channels up to a maximum of 64 per VM. In this
100 example, each DPDK lcore on a VM has exclusive access to a channel.
102 To enable frequency changes from within a VM, the VM forwards a
103 ``librte_power`` request over the ``virtio-serial`` channel to the host. Each
104 request contains the vCPU and power command (scale up/down/min/max). The
105 API for the host ``librte_power`` and guest ``librte_power`` is consistent
106 across environments, with the selection of VM or host implementation
107 determined automatically at runtime based on the environment. On
108 receiving a request, the host translates the vCPU to a pCPU using the
109 libvirt API before forwarding it to the host ``librte_power``.
112 .. _figure_vm_power_mgr_vm_request_seq:
114 .. figure:: img/vm_power_mgr_vm_request_seq.*
116 In addition to the ability to send power management requests to the
117 host, a VM can send a power management policy to the host. In some
118 cases, using a power management policy is a preferred option because it
119 can eliminate possible latency issues that can occur when sending power
120 management requests. Once the VM sends the policy to the host, the VM no
121 longer needs to worry about power management, because the host now
122 manages the power for the VM based on the policy. The policy can specify
123 power behavior that is based on incoming traffic rates or time-of-day
124 power adjustment (busy/quiet hour power adjustment for example). See
125 :ref:`sending_policy` for more information.
127 One method of power management is to sense how busy a core is when
128 processing packets and adjusting power accordingly. One technique for
129 doing this is to monitor the ratio of the branch miss to branch hits
130 counters and scale the core power accordingly. This technique is based
131 on the premise that when a core is not processing packets, the ratio of
132 branch misses to branch hits is very low, but when the core is
133 processing packets, it is measurably higher. The implementation of this
134 capability is as a policy of type ``BRANCH_RATIO``.
135 See :ref:`sending_policy` for more information on using the
136 BRANCH_RATIO policy option.
138 A JSON interface enables the specification of power management requests
139 and policies in JSON format. The JSON interfaces provide a more
140 convenient and more easily interpreted interface for the specification
141 of requests and policies. See :ref:`power_man_requests` for more information.
143 Performance Considerations
144 ~~~~~~~~~~~~~~~~~~~~~~~~~~
146 While the Haswell microarchitecture allows for independent power control
147 for each core, earlier microarchitectures do not offer such fine-grained
148 control. When deploying on pre-Haswell platforms, greater care must be
149 taken when selecting which cores are assigned to a VM, for example, a
150 core does not scale down in frequency until all of its siblings are
151 similarly scaled down.
159 To use the power management features of the DPDK, you must enable
160 Enhanced Intel SpeedStep® Technology in the platform BIOS. Otherwise,
161 the ``sys`` file folder ``/sys/devices/system/cpu/cpu0/cpufreq`` does not
162 exist, and you cannot use CPU frequency-based power management. Refer to the
163 relevant BIOS documentation to determine how to access these settings.
165 Host Operating System
166 ~~~~~~~~~~~~~~~~~~~~~
168 The DPDK Power Management library can use either the ``acpi_cpufreq`` or
169 the ``intel_pstate`` kernel driver for the management of core frequencies. In
170 many cases, the ``intel_pstate`` driver is the default power management
173 Should the ``acpi-cpufreq driver`` be required, the ``intel_pstate``
174 module must be disabled, and the ``acpi-cpufreq`` module loaded in its place.
176 To disable the ``intel_pstate`` driver, add the following to the ``grub``
179 ``intel_pstate=disable``
181 On reboot, load the ``acpi_cpufreq`` module:
183 ``modprobe acpi_cpufreq``
185 Hypervisor Channel Configuration
186 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
188 Configure ``virtio-serial`` channels using ``libvirt`` XML.
189 The XML structure is as follows:
193 <name>{vm_name}</name>
194 <controller type='virtio-serial' index='0'>
195 <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
197 <channel type='unix'>
198 <source mode='bind' path='/tmp/powermonitor/{vm_name}.{channel_num}'/>
199 <target type='virtio' name='virtio.serial.port.poweragent.{vm_channel_num}'/>
200 <address type='virtio-serial' controller='0' bus='0' port='{N}'/>
203 Where a single controller of type ``virtio-serial`` is created, up to 32
204 channels can be associated with a single controller, and multiple
205 controllers can be specified. The convention is to use the name of the
206 VM in the host path ``{vm_name}`` and to increment ``{channel_num}`` for each
207 channel. Likewise, the port value ``{N}`` must be incremented for each
210 On the host, for each channel to appear in the path, ensure the creation
211 of the ``/tmp/powermonitor/`` directory and the assignment of ``qemu``
214 .. code-block:: console
216 mkdir /tmp/powermonitor/
217 chown qemu:qemu /tmp/powermonitor
219 Note that files and directories in ``/tmp`` are generally removed when
220 rebooting the host and you may need to perform the previous steps after
223 The serial device as it appears on a VM is configured with the target
224 element attribute name and must be in the form:
225 ``virtio.serial.port.poweragent.{vm_channel_num}``, where
226 ``vm_channel_num`` is typically the lcore channel to be used in
227 DPDK VM applications.
229 Each channel on a VM is present at:
231 ``/dev/virtio-ports/virtio.serial.port.poweragent.{vm_channel_num}``
233 Compiling and Running the Host Application
234 ------------------------------------------
236 Compiling the Host Application
237 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
239 For information on compiling the DPDK and sample applications,
240 see :doc:`compiling`.
242 The application is located in the ``vm_power_manager`` subdirectory.
244 To build just the ``vm_power_manager`` application using ``make``:
246 .. code-block:: console
248 cd dpdk/examples/vm_power_manager/
251 The resulting binary is ``dpdk/build/examples/vm_power_manager``.
253 To build just the ``vm_power_manager`` application using ``meson``/``ninja``:
255 .. code-block:: console
261 meson configure -Dexamples=vm_power_manager
264 The resulting binary is ``dpdk/build/examples/dpdk-vm_power_manager``.
266 Running the Host Application
267 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
269 The application does not have any specific command line options other
270 than the EAL options:
272 .. code-block:: console
274 ./<build_dir>/examples/dpdk-vm_power_mgr [EAL options]
276 The application requires exactly two cores to run. One core for the CLI
277 and the other for the channel endpoint monitor. For example, to run on
278 cores 0 and 1 on a system with four memory channels, issue the command:
280 .. code-block:: console
282 ./<build_dir>/examples/dpdk-vm_power_mgr -l 0-1 -n 4
284 After successful initialization, the VM Power Manager CLI prompt appears:
286 .. code-block:: console
290 Now, it is possible to add virtual machines to the VM Power Manager:
292 .. code-block:: console
294 vm_power> add_vm {vm_name}
296 When a ``{vm_name}`` is specified with the ``add_vm`` command, a lookup is
297 performed with ``libvirt`` to ensure that the VM exists. ``{vm_name}`` is a
298 unique identifier to associate channels with a particular VM and for
299 executing operations on a VM within the CLI. VMs do not have to be
302 It is possible to issue several commands from the CLI to manage VMs.
304 Remove the virtual machine identified by ``{vm_name}`` from the VM Power
305 Manager using the command:
307 .. code-block:: console
311 Add communication channels for the specified VM using the following
312 command. The ``virtio`` channels must be enabled in the VM configuration
313 (``qemu/libvirt``) and the associated VM must be active. ``{list}`` is a
314 comma-separated list of channel numbers to add. Specifying the keyword
315 ``all`` attempts to add all channels for the VM:
317 .. code-block:: console
319 set_pcpu {vm_name} {vcpu} {pcpu}
321 Enable query of physical core information from a VM:
323 .. code-block:: console
325 set_query {vm_name} enable|disable
327 Manual control and inspection can also be carried in relation CPU frequency scaling:
329 Get the current frequency for each core specified in the mask:
331 .. code-block:: console
333 show_cpu_freq_mask {mask}
335 Set the current frequency for the cores specified in {core_mask} by scaling each up/down/min/max:
337 .. code-block:: console
339 add_channels {vm_name} {list}|all
341 Enable or disable the communication channels in ``{list}`` (comma-separated)
342 for the specified VM. Alternatively, replace ``list`` with the keyword
343 ``all``. Disabled channels receive packets on the host. However, the commands
344 they specify are ignored. Set the status to enabled to begin processing
347 .. code-block:: console
349 set_channel_status {vm_name} {list}|all enabled|disabled
351 Print to the CLI information on the specified VM. The information lists
352 the number of vCPUs, the pinning to pCPU(s) as a bit mask, along with
353 any communication channels associated with each VM, and the status of
356 .. code-block:: console
360 Set the binding of a virtual CPU on a VM with name ``{vm_name}`` to the
363 .. code-block:: console
365 set_pcpu_mask {vm_name} {vcpu} {pcpu}
367 Set the binding of the virtual CPU on the VM to the physical CPU:
369 .. code-block:: console
371 set_pcpu {vm_name} {vcpu} {pcpu}
373 It is also possible to perform manual control and inspection in relation
374 to CPU frequency scaling.
376 Get the current frequency for each core specified in the mask:
378 .. code-block:: console
380 show_cpu_freq_mask {mask}
382 Set the current frequency for the cores specified in ``{core_mask}`` by
383 scaling each up/down/min/max:
385 .. code-block:: console
387 set_cpu_freq {core_mask} up|down|min|max
389 Get the current frequency for the specified core:
391 .. code-block:: console
393 show_cpu_freq {core_num}
395 Set the current frequency for the specified core by scaling up/down/min/max:
397 .. code-block:: console
399 set_cpu_freq {core_num} up|down|min|max
401 .. _enabling_out_of_band:
403 Command Line Options for Enabling Out-of-band Branch Ratio Monitoring
404 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
406 There are a couple of command line parameters for enabling the out-of-band
407 monitoring of branch ratios on cores doing busy polling using PMDs as
410 ``--core-branch-ratio {list of cores}:{branch ratio for listed cores}``
411 Specify the list of cores to monitor the ratio of branch misses
412 to branch hits. A tightly-polling PMD thread has a very low
413 branch ratio, therefore the core frequency scales down to the
414 minimum allowed value. On receiving packets, the code path changes,
415 causing the branch ratio to increase. When the ratio goes above
416 the ratio threshold, the core frequency scales up to the maximum
417 allowed value. The specified branch-ratio is a floating point number
418 that identifies the threshold at which to scale up or down for the
419 elements of the core-list. If not included the default branch ratio of
420 0.01 but will need adjustment for different workloads
422 This parameter can be used multiple times for different sets of cores.
423 The branch ratio mechanism can also be useful for non-PMD cores and
424 hyper-threaded environments where C-States are disabled.
427 Compiling and Running the Guest Applications
428 --------------------------------------------
430 It is possible to use the ``l3fwd-power`` application (for example) with the
431 ``vm_power_manager``.
433 The distribution also provides a guest CLI for validating the setup.
435 For both ``l3fwd-power`` and the guest CLI, the host application must use
436 the ``add_channels`` command to monitor the channels for the VM. To do this,
437 issue the following commands in the host application:
439 .. code-block:: console
441 vm_power> add_vm vmname
442 vm_power> add_channels vmname all
443 vm_power> set_channel_status vmname all enabled
444 vm_power> show_vm vmname
446 Compiling the Guest Application
447 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
449 For information on compiling DPDK and the sample applications in general,
450 see :doc:`compiling`.
452 For compiling and running the ``l3fwd-power`` sample application, see
453 :doc:`l3_forward_power_man`.
455 The application is in the ``guest_cli`` subdirectory under ``vm_power_manager``.
457 To build just the ``guest_vm_power_manager`` application using ``make``, issue
458 the following commands:
460 .. code-block:: console
462 cd dpdk/examples/vm_power_manager/guest_cli/
465 The resulting binary is ``dpdk/build/examples/guest_cli``.
467 **Note**: This sample application conditionally links in the Jansson JSON
468 library. Consequently, if you are using a multilib or cross-compile
469 environment, you may need to set the ``PKG_CONFIG_LIBDIR`` environmental
470 variable to point to the relevant ``pkgconfig`` folder so that the correct
471 library is linked in.
473 For example, if you are building for a 32-bit target, you could find the
474 correct directory using the following find command:
476 .. code-block:: console
478 # find /usr -type d -name pkgconfig
479 /usr/lib/i386-linux-gnu/pkgconfig
480 /usr/lib/x86_64-linux-gnu/pkgconfig
484 .. code-block:: console
486 export PKG_CONFIG_LIBDIR=/usr/lib/i386-linux-gnu/pkgconfig
488 You then use the ``make`` command as normal, which should find the 32-bit
489 version of the library, if it installed. If not, the application builds
490 without the JSON interface functionality.
492 To build just the ``vm_power_manager`` application using ``meson``/``ninja``:
494 .. code-block:: console
500 meson configure -Dexamples=vm_power_manager/guest_cli
503 The resulting binary is ``dpdk/build/examples/guest_cli``.
505 Running the Guest Application
506 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
508 The standard EAL command line parameters are necessary:
510 .. code-block:: console
512 ./<build_dir>/examples/dpdk-vm_power_mgr [EAL options] -- [guest options]
514 The guest example uses a channel for each lcore enabled. For example, to
515 run on cores 0, 1, 2 and 3:
517 .. code-block:: console
519 ./<build_dir>/examples/dpdk-guest_vm_power_mgr -l 0-3
523 Command Line Options Available When Sending a Policy to the Host
524 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
526 Optionally, there are several command line options for a user who needs
527 to send a power policy to the host application:
529 ``--vm-name {name of guest vm}``
530 Allows the user to change the virtual machine name
531 passed down to the host application using the power policy.
532 The default is ubuntu2.
534 ``--vcpu-list {list vm cores}``
535 A comma-separated list of cores in the VM that the user
536 wants the host application to monitor.
537 The list of cores in any VM starts at zero,
538 and the host application maps these to the physical cores
539 once the policy passes down to the host.
540 Valid syntax includes individual cores 2,3,4,
541 a range of cores 2-4, or a combination of both 1,3,5-7.
543 ``--busy-hours {list of busy hours}``
544 A comma-separated list of hours in which to set the core
545 frequency to the maximum.
546 Valid syntax includes individual hours 2,3,4,
547 a range of hours 2-4, or a combination of both 1,3,5-7.
548 Valid hour values are 0 to 23.
550 ``--quiet-hours {list of quiet hours}``
551 A comma-separated list of hours in which to set the core frequency
552 to minimum. Valid syntax includes individual hours 2,3,4,
553 a range of hours 2-4, or a combination of both 1,3,5-7.
554 Valid hour values are 0 to 23.
556 ``--policy {policy type}``
557 The type of policy. This can be one of the following values:
559 - TRAFFIC - Based on incoming traffic rates on the NIC.
560 - TIME - Uses a busy/quiet hours policy.
561 - BRANCH_RATIO - Uses branch ratio counters to determine core busyness.
562 - WORKLOAD - Sets the frequency to low, medium or high
563 based on the received policy setting.
565 **Note**: Not all policy types need all parameters.
566 For example, BRANCH_RATIO only needs the vcpu-list parameter.
568 After successful initialization, the VM Power Manager Guest CLI prompt
571 .. code-block:: console
575 To change the frequency of an lcore, use a ``set_cpu_freq`` command similar
578 .. code-block:: console
580 set_cpu_freq {core_num} up|down|min|max
582 where, ``{core_num}`` is the lcore and channel to change frequency by
583 scaling up/down/min/max.
585 To start an application, configure the power policy, and send it to the
586 host, use a command like the following:
588 .. code-block:: console
590 ./<build_dir>/examples/dpdk-guest_vm_power_mgr -l 0-3 -n 4 -- --vm-name=ubuntu --policy=BRANCH_RATIO --vcpu-list=2-4
592 Once the VM Power Manager Guest CLI appears, issuing the 'send_policy now' command
593 will send the policy to the host:
595 .. code-block:: console
599 Once the policy is sent to the host, the host application takes over the power monitoring
600 of the specified cores in the policy.
602 .. _power_man_requests:
604 JSON Interface for Power Management Requests and Policies
605 ---------------------------------------------------------
607 In addition to the command line interface for the host command, and a
608 ``virtio-serial`` interface for VM power policies, there is also a JSON
609 interface through which power commands and policies can be sent.
611 **Note**: This functionality adds a dependency on the Jansson library.
612 Install the Jansson development package on the system to avail of the
613 JSON parsing functionality in the app. Issue the ``apt-get install
614 libjansson-dev`` command to install the development package. The command
615 and package name may be different depending on your operating system. It
616 is worth noting that the app builds successfully if this package is not
617 present, but a warning displays during compilation, and the JSON parsing
618 functionality is not present in the app.
620 Send a request or policy to the VM Power Manager by simply opening a
621 fifo file at ``/tmp/powermonitor/fifo``, writing a JSON string to that file,
622 and closing the file.
624 The JSON string can be a power management request or a policy, and takes
625 the following format:
627 .. code-block:: javascript
634 The ``packet_type`` header can contain one of two values, depending on
635 whether a power management request or policy is being sent. The two
636 possible values are ``instruction`` and ``policy`` and the expected name-value
637 pairs are different depending on which type is sent.
639 The pairs are in the format of standard JSON name-value pairs. The value
640 type varies between the different name-value pairs, and may be integers,
641 strings, arrays, and so on. See :ref:`json_interface_ex`
642 for examples of policies and instructions and
643 :ref:`json_name_value_pair` for the supported names and value types.
645 .. _json_interface_ex:
647 JSON Interface Examples
648 ~~~~~~~~~~~~~~~~~~~~~~~
650 The following is an example JSON string that creates a time-profile
658 "policy_type": "TIME",
659 "busy_hours":[ 17, 18, 19, 20, 21, 22, 23 ],
660 "quiet_hours":[ 2, 3, 4, 5, 6 ],
664 The following is an example JSON string that removes the named policy.
670 "command": "destroy",
673 The following is an example JSON string for a power management request.
684 To query the available frequencies of an lcore, use the query_cpu_freq command.
685 Where {core_num} is the lcore to query.
686 Before using this command, please enable responses via the set_query command on the host.
688 .. code-block:: console
690 query_cpu_freq {core_num}|all
692 To query the capabilities of an lcore, use the query_cpu_caps command.
693 Where {core_num} is the lcore to query.
694 Before using this command, please enable responses via the set_query command on the host.
696 .. code-block:: console
698 query_cpu_caps {core_num}|all
700 To start the application and configure the power policy, and send it to the host:
702 .. code-block:: console
704 ./<build_dir>/examples/dpdk-guest_vm_power_mgr -l 0-3 -n 4 -- --vm-name=ubuntu --policy=BRANCH_RATIO --vcpu-list=2-4
706 Once the VM Power Manager Guest CLI appears, issuing the 'send_policy now' command
707 will send the policy to the host:
709 .. code-block:: console
713 Once the policy is sent to the host, the host application takes over the power monitoring
714 of the specified cores in the policy.
716 .. _json_name_value_pair:
718 JSON Name-value Pairs
719 ~~~~~~~~~~~~~~~~~~~~~
721 The following are the name-value pairs supported by the JSON interface:
723 - `avg_packet_thresh`_
728 - `max_packet_thresh`_
740 The threshold below which the frequency is set to the minimum value
741 for the TRAFFIC policy.
742 If the traffic rate is above this value and below the maximum value,
743 the frequency is set to medium.
747 The number of packets below which the TRAFFIC policy applies
748 the minimum frequency, or the medium frequency
749 if between the average and maximum thresholds.
753 ``"avg_packet_thresh": 100000``
759 The hours of the day in which we scale up the cores for busy times.
763 An array with a list of hour values (0-23).
765 For the TIME policy only.
767 ``"busy_hours":[ 17, 18, 19, 20, 21, 22, 23 ]``
773 The type of packet to send to the VM Power Manager.
774 It is possible to create or destroy a policy or send a direct command
775 to adjust the frequency of a core,
776 as is possible on the command line interface.
781 - CREATE: Create a new policy.
782 - DESTROY: Remove an existing policy.
783 - POWER: Send an immediate command, max, min, and so on.
787 ``"command": "CREATE"``
793 The cores to which to apply a policy.
797 An array with a list of virtual CPUs.
799 For CREATE/DESTROY policy requests only.
801 ``"core_list":[ 10, 11 ]``
807 When the policy is of type TRAFFIC,
808 it is necessary to specify the MAC addresses that the host must monitor.
812 An array with a list of MAC address strings.
814 For TRAFFIC policy types only.
816 ``"mac_list":[ "de:ad:be:ef:01:01","de:ad:be:ef:01:02" ]``
822 In a policy of type TRAFFIC,
823 the threshold value above which the frequency is set to a maximum.
827 The number of packets per interval above which
828 the TRAFFIC policy applies the maximum frequency.
830 For the TRAFFIC policy only.
832 ``"max_packet_thresh": 500000``
838 The name of the VM or host.
839 Allows the parser to associate the policy with the relevant VM or host OS.
847 ``"name": "ubuntu2"``
853 The type of policy to apply.
854 See the ``--policy`` option description for more information.
860 - TIME: Time-of-day policy.
861 Scale the frequencies of the relevant cores up/down
862 depending on busy and quiet hours.
863 - TRAFFIC: Use statistics from the NIC and scale up and down accordingly.
864 - WORKLOAD: Determine how heavily loaded the cores are
865 and scale up and down accordingly.
866 - BRANCH_RATIO: An out-of-band policy that looks at the ratio
867 between branch hits and misses on a core
868 and uses that information to determine how much packet processing
872 For ``CREATE`` and ``DESTROY`` policy requests only.
874 ``"policy_type": "TIME"``
880 The hours of the day to scale down the cores for quiet times.
884 An array with a list of hour numbers with values in the range 0 to 23.
886 For the TIME policy only.
888 ``"quiet_hours":[ 2, 3, 4, 5, 6 ]``
894 The core to which to apply a power command.
898 A valid core ID for the VM or host OS.
900 For the ``POWER`` instruction only.
902 ``"resource_id": 10``
908 The type of power operation to apply in the command.
912 - SCALE_MAX: Scale the frequency of this core to the maximum.
913 - SCALE_MIN: Scale the frequency of this core to the minimum.
914 - SCALE_UP: Scale up the frequency of this core.
915 - SCALE_DOWN: Scale down the frequency of this core.
916 - ENABLE_TURBO: Enable Intel® Turbo Boost Technology for this core.
917 - DISABLE_TURBO: Disable Intel® Turbo Boost Technology for this core.
919 For the ``POWER`` instruction only.
921 ``"unit": "SCALE_MAX"``
927 In a policy of type WORKLOAD,
928 it is necessary to specify how heavy the workload is.
932 - HIGH: Scale the frequency of this core to maximum.
933 - MEDIUM: Scale the frequency of this core to minimum.
934 - LOW: Scale up the frequency of this core.
936 For the ``WORKLOAD`` policy only.
938 ``"workload": "MEDIUM"``