Configuring SBC SWe in OpenStack Cloud Environment for GPU Transcoding

Supported Deployment Scenarios

GPU acceleration is supported on SBC SWe I-SBC and T-SBC instances on OpenStack (Newton and above). T-SBC is a component in a Distributed SBC architecture that provides transcoding service.

GPU devices are attached to SBC cloud instances through PCIe pass-through – a single GPU device can be used by only one instance at a time. The process of enabling PCIe pass-through in OpenStack is detailed later in this document. For performance considerations, NUMA locality of devices should be ensured.

Supported GPU Devices

NVIDIA Tesla V100(PCIe)

Supported Codecs

The following codecs are supported:

• GPU + CPU codecs : AMR-NB, AMR-WB, EVRC, EVRCB, G729, G722, G711
• CPU only codecs :  G723, G726, G7221, ILBC, OPUS, SILK_8, SILK_16, EVS, G7112G711, T38

For more information on "GPU + CPU codecs", see the section Support for CPU+GPU Hybrid Transcoding Instances.

Support for CPU+GPU Hybrid Transcoding Instances

The term "Hybrid Transcoding" implies leveraging both CPU and GPU resources efficiently to accommodate a given codec combination for transcoding capability. With Hybrid Transcoding, a suitable VM instance (SBC SWe on KVM/Openstack) utilizes all the CPU and GPU resources allocated to it for provisioning a given transcode call mix scenario.

Prior to Hybrid Transcoding, the SBC supported either a pure CPU transcoding solution, or a pure GPU transcoding solution. However, in the pure GPU solution, many CPUs are left unused. For example, when a 32 vCPU, GPU-ISBC instance is used to provision just AMRWB-G711u calls, only 13 vCPUs are used, although such an instance can handle 7680 sessions for AMRWB-G711u transcoding. With Hybrid Transcoding, the remaining 19 vCPUs (32-13 vCPUs) are used for provisioning additional AMRWB-G711 sessions.

Hybrid Transcoding enables a GPU-SBC to support GPU codecs as well as non-GPU-supported codec in the same instance. For example, AMRWB-G711 and G726-G711 codecs are supported in the same instance. 

Hybrid Transcoding is supported in Custom GPU and Standard GPU traffic profiles.

For Hybrid Transcoding, the percentage value of the codec G7112G711 in sweCodecMixProfile indicates the proportion of total number of sessions designated for pure G711 transcoding (G711-G711). This is applicable for Hybrid Transcoding, as well as pure CPU transcoding solutions.

Best Practice

Ribbon recommends monitoring of the status of codec channel capacities for codecs provisioned on GPU (on a per GPU device basis), as well as on CPU.

• To display the status of codec channel capacities for codecs provisioned on GPU, on a per GPU device basis, execute the following existing command:

  > show table system gpuTranscodeStatus

• Similarly, to display the status of codec channel capacities for codecs provisioned on CPU, execute the following existing command:

  > show table system cpuTranscodeStatus

To display the status using the EMA, refer to:

• System - Cpu Transcode Status
• System - Gpu Transcode Status

Instantiating GPU T-SBC on OpenStack Cloud

The T-SBC is instantiated using the help of a specific heat template.  The GPU T-SBC requires a special flavor that has appropriate directives to utilize GPU devices of the compute node available for PCIe pass-through.

T-SBC Heat Template

The T-SBC instance should be launched using the heatRgNoDhcp-TSBC-template.yaml template. This template shares all fields of an M-SBC template, and additionally has the following fields:

Host Changes on OpenStack for Enabling GPU Devices

This section describes the changes needed on the Controller node and the Compute node hosting GPU cards in order to enable instances to use GPU devices. While this section focuses purely on the GPU aspect, Ribbon recommends that you refer to broader OpenStack performance tuning recommendations covered in the following links:

• VNF Performance Tuning
• Pre-Instantiation Requirements of OpenStack

intel_iommu=on iommu=pt rdblacklist=nouveau

grub2-mkconfig -o /etc/grub2.cfg

blacklist nouveau

pci_alias={"vendor_id":"10de", "product_id":"1db4","device_type":"type-PCI", "name":"v100gpu"}

systemctl restart OpenStack-nova-api.service

Guideline for Creating Flavors for GPU T-SBC Instances

Open the dashboard and create a flavor with the following properties. Check with your Ribbon account team to determine the appropriate instance size for your traffic needs.

After creating the flavor, update its metadata with the following key values.

Configuring the SBC for Invoking T-SBC

Refer to the following pages for basic configuration steps for the S-SBC and M-SBC:

• S-SBC Cluster Configuration using SBC Configuration Manager
• M-SBC Cluster Configuration using SBC Configuration Manager
• Instantiating SBC SWe on OpenStack using Heat Templates

For enabling T-SBC, some additional configurations are required in S-SBC and M-SBC which are described in subsequent sections.

Configuring and Activating T-SBC Cluster

Steps for configuration of T-SBC is similar to M-SBC with the following exception: The IP interface group creation procedure should create private interface groups instead of public. There are no public interface groups for T-SBC.

Additional Configuration for S-SBC

A DSP cluster needs to be configured in the S-SBC configuration to refer to the T-SBC cluster that is to be used for transcoding. The following steps describe the procedure for creation of this cluster:

Additional Configuration for M-SBC

Configure the private IP interface group for relaying media packets to T-SBC using steps from the "Configure Private LIF Groups in M-SBC" section of Invoke MRF as a Transcoder for D-SBC.

Licensing

All pre-existing licensing related to transcoding apply to GPU codecs as well. There is no separate license for GPU functionality.