1.. SPDX-License-Identifier: BSD-3-Clause 2 Copyright(c) 2017 Intel Corporation. 3 4Service Cores 5============= 6 7DPDK has a concept known as service cores, which enables a dynamic way of 8performing work on DPDK lcores. Service core support is built into the EAL, and 9an API is provided to optionally allow applications to control how the service 10cores are used at runtime. 11 12The service cores concept is built up out of services (components of DPDK that 13require CPU cycles to operate) and service cores (DPDK lcores, tasked with 14running services). The power of the service core concept is that the mapping 15between service cores and services can be configured to abstract away the 16difference between platforms and environments. 17 18For example, the Eventdev has hardware and software PMDs. Of these the software 19PMD requires an lcore to perform the scheduling operations, while the hardware 20PMD does not. With service cores, the application would not directly notice 21that the scheduling is done in software. 22 23For detailed information about the service core API, please refer to the docs. 24 25Service Core Initialization 26~~~~~~~~~~~~~~~~~~~~~~~~~~~ 27 28There are two methods to having service cores in a DPDK application, either by 29using the service coremask, or by dynamically adding cores using the API. 30The simpler of the two is to pass the `-s` coremask argument to EAL, which will 31take any cores available in the main DPDK coremask, and if the bits are also set 32in the service coremask the cores become service-cores instead of DPDK 33application lcores. 34 35Enabling Services on Cores 36~~~~~~~~~~~~~~~~~~~~~~~~~~ 37 38Each registered service can be individually mapped to a service core, or set of 39service cores. Enabling a service on a particular core means that the lcore in 40question will run the service. Disabling that core on the service stops the 41lcore in question from running the service. 42 43Using this method, it is possible to assign specific workloads to each 44service core, and map N workloads to M number of service cores. Each service 45lcore loops over the services that are enabled for that core, and invokes the 46function to run the service. 47 48Service Core Statistics 49~~~~~~~~~~~~~~~~~~~~~~~ 50 51The service core library is capable of collecting runtime statistics like number 52of calls to a specific service, and number of cycles used by the service. The 53cycle count collection is dynamically configurable, allowing any application to 54profile the services running on the system at any time. 55