doc: update VM power manager sample guide
Add information on the ability of guest app to sent a policy to the host app. Add information on the branch ratio out-of-band method of workload monitoring and power management. Signed-off-by: David Hunt <david.hunt@intel.com> Acked-by: John McNamara <john.mcnamara@intel.com>
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David Hunt
Thomas Monjalon
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50ac590ff8
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@ -20,7 +20,7 @@ running on Virtual Machines(VMs).
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The Virtual Machine Power Management solution shows an example of
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how a DPDK application can indicate its processing requirements using VM local
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only information(vCPU/lcore) to a Host based Monitor which is responsible
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only information(vCPU/lcore, etc.) to a Host based Monitor which is responsible
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for accepting requests for frequency changes for a vCPU, translating the vCPU
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to a pCPU via libvirt and affecting the change in frequency.
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@ -38,6 +38,26 @@ The solution is comprised of two high-level components:
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to the librte_power ACPI cpufreq sysfs based library.
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The Host Application relies on both qemu-kvm and libvirt to function.
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This monitoring application is responsible for:
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- Accepting requests from client applications: Client applications can
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request frequency changes for a vCPU, translating
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the vCPU to a pCPU via libvirt and affecting the change in frequency.
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- Accepting policies from client applications: Client application can
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send a policy to the host application. The
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host application will then apply the rules of the policy independent
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of the application. For example, the policy can contain time-of-day
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information for busy/quiet periods, and the host application can scale
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up/down the relevant cores when required. See the details of the guest
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application below for more information on setting the policy values.
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- Out-of-band monitoring of workloads via cores hardware event counters:
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The host application can manage power for an application in a virtualised
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OR non-virtualised environment by looking at the event counters of the
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cores and taking action based on the branch hit/miss ratio. See the host
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application '--core-list' command line parameter below.
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#. librte_power for Virtual Machines
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Using an alternate implementation for the librte_power API, requests for
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@ -174,13 +194,20 @@ Compiling and Running the Host Application
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Compiling
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~~~~~~~~~
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Compiling the Application
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-------------------------
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To compile the sample application see :doc:`compiling`.
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For information on compiling DPDK and the sample applications
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see :doc:`compiling`.
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The application is located in the ``vm_power_manager`` sub-directory.
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To build just the ``vm_power_manager`` application:
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.. code-block:: console
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export RTE_SDK=/path/to/rte_sdk
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export RTE_TARGET=build
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cd ${RTE_SDK}/examples/vm_power_manager/
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make
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Running
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~~~~~~~
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@ -287,38 +314,129 @@ Manual control and inspection can also be carried in relation CPU frequency scal
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set_cpu_freq {core_num} up|down|min|max
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There are also some command line parameters for enabling the out-of-band
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monitoring of branch ratio on cores doing busy polling via PMDs.
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.. code-block:: console
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--core-list {list of cores}
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When this parameter is used, the list of cores specified will monitor the ratio
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between branch hits and branch misses. A tightly polling PMD thread will have a
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very low branch ratio, so the core frequency will be scaled down to the minimim
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allowed value. When packets are received, the code path will alter, causing the
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branch ratio to increase. When the ratio goes above the ratio threshold, the
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core frequency will be scaled up to the maximum allowed value.
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.. code-block:: console
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--branch-ratio {ratio}
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The branch ratio is a floating point number that specifies the threshold at which
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to scale up or down for the given workload. The default branch ratio is 0.01,
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and will need to be adjusted for different workloads.
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Compiling and Running the Guest Applications
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--------------------------------------------
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For compiling and running l3fwd-power, see :doc:`l3_forward_power_man`.
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l3fwd-power is one sample application that can be used with vm_power_manager.
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A guest CLI is also provided for validating the setup.
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For both l3fwd-power and guest CLI, the channels for the VM must be monitored by the
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host application using the *add_channels* command on the host.
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host application using the *add_channels* command on the host. This typically uses
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the following commands in the host application:
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.. code-block:: console
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vm_power> add_vm vmname
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vm_power> add_channels vmname all
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vm_power> set_channel_status vmname all enabled
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vm_power> show_vm vmname
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Compiling
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~~~~~~~~~
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#. export RTE_SDK=/path/to/rte_sdk
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#. cd ${RTE_SDK}/examples/vm_power_manager/guest_cli
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#. make
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For information on compiling DPDK and the sample applications
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see :doc:`compiling`.
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For compiling and running l3fwd-power, see :doc:`l3_forward_power_man`.
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The application is located in the ``guest_cli`` sub-directory under ``vm_power_manager``.
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To build just the ``guest_vm_power_manager`` application:
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.. code-block:: console
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export RTE_SDK=/path/to/rte_sdk
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export RTE_TARGET=build
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cd ${RTE_SDK}/examples/vm_power_manager/guest_cli/
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make
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Running
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~~~~~~~
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The application does not have any specific command line options other than *EAL*:
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The standard *EAL* command line parameters are required:
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.. code-block:: console
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./build/vm_power_mgr [EAL options]
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./build/guest_vm_power_mgr [EAL options] -- [guest options]
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The application for example purposes uses a channel for each lcore enabled,
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for example to run on cores 0,1,2,3 on a system with 4 memory channels:
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The guest example uses a channel for each lcore enabled. For example,
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to run on cores 0,1,2,3:
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.. code-block:: console
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./build/guest_vm_power_mgr -l 0-3 -n 4
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./build/guest_vm_power_mgr -l 0-3
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Optionally, there is a list of command line parameter should the user wish to send a power
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policy down to the host application. These parameters are as follows:
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.. code-block:: console
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--vm-name {name of guest vm}
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This parameter allows the user to change the Virtual Machine name passed down to the
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host application via the power policy. The default is "ubuntu2"
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.. code-block:: console
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--vcpu-list {list vm cores}
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A comma-separated list of cores in the VM that the user wants the host application to
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monitor. The list of cores in any vm starts at zero, and these are mapped to the
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physical cores by the host application once the policy is passed down.
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Valid syntax includes individial cores '2,3,4', or a range of cores '2-4', or a
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combination of both '1,3,5-7'
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.. code-block:: console
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--busy-hours {list of busy hours}
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A comma-separated list of hours within which to set the core frequency to maximum.
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Valid syntax includes individial hours '2,3,4', or a range of hours '2-4', or a
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combination of both '1,3,5-7'. Valid hours are 0 to 23.
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.. code-block:: console
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--quiet-hours {list of quiet hours}
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A comma-separated list of hours within which to set the core frequency to minimum.
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Valid syntax includes individial hours '2,3,4', or a range of hours '2-4', or a
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combination of both '1,3,5-7'. Valid hours are 0 to 23.
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.. code-block:: console
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--policy {policy type}
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The type of policy. This can be one of the following values:
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TRAFFIC - based on incoming traffic rates on the NIC.
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TIME - busy/quiet hours policy.
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BRANCH_RATIO - uses branch ratio counters to determine core busyness.
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Not all parameters are needed for all policy types. For example, BRANCH_RATIO
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only needs the vcpu-list parameter, not any of the hours.
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After successful initialization the user is presented with VM Power Manager Guest CLI:
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@ -333,3 +451,20 @@ Where {core_num} is the lcore and channel to change frequency by scaling up/down
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.. code-block:: console
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set_cpu_freq {core_num} up|down|min|max
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To start the application and configure the power policy, and send it to the host:
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.. code-block:: console
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./build/guest_vm_power_mgr -l 0-3 -n 4 -- --vm-name=ubuntu --policy=BRANCH_RATIO --vcpu-list=2-4
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Once the VM Power Manager Guest CLI appears, issuing the 'send_policy now' command
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will send the policy to the host:
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.. code-block:: console
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send_policy now
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Once the policy is sent to the host, the host application takes over the power monitoring
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of the specified cores in the policy.
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