CoreMark

The sample demonstrates how to run the CoreMark® benchmark to evaluate the performance of a core. To get started with CoreMark integration in nRF Connect SDK, see CoreMark integration.

Requirements 

The sample supports the following development kits:

Hardware platforms	PCA	Board name	Build target
nRF54L15 PDK	PCA10156	nrf54l15pdk	`nrf54l15pdk/nrf54l15/cpuapp` `nrf54l15pdk@0.3.0/nrf54l15/cpuapp`
nRF5340 DK	PCA10095	nrf5340dk	`nrf5340dk/nrf5340/cpuapp`
nRF52 DK	PCA10040	nrf52dk	`nrf52dk/nrf52832`
nRF52840 DK	PCA10056	nrf52840dk	`nrf52840dk/nrf52840`

The sample runs the CoreMark benchmark on the target CPU. CoreMark evaluates the CPU efficiency by performing different algorithms, such as state machine, CRC calculation, matrix manipulation, and list processing (find and sort).

To run the CoreMark benchmark on the preferred core, press the corresponding button. For the button assignment, see the User interface section. When the benchmark has completed, you can press the same button to restart it. If you want to run the sample upon startup, enable the CONFIG_APP_MODE_FLASH_AND_RUN Kconfig option.

User interface 

Each target CPU has an assigned button responsible for starting the benchmark and LED that indicates the test in progress state:

Button 1:: Start the benchmark run on the application core.
Button 2:: Start the benchmark run on the network or radio core.
Button 3:: Start the benchmark run on the PPR core.
LED 1:: Indicates test in progress on the application core.
LED 2:: Indicates test in progress on the network or radio core.
LED 3:: Indicates test in progress on the PPR core.

Configuration 

See Configuring and building an application for information about how to permanently or temporarily change the configuration.

CoreMark runs tests multiple times. You can define the number of iterations using the CONFIG_COREMARK_ITERATIONS Kconfig option. By default, the iteration quantity is set to the minimum time required for valid results, which is 10 seconds.

Additional configuration 

Check and configure the following configuration options that are used by the sample:

Run types and data sizes

CoreMark has the following predefined run types and data sizes that are used for data algorithms:

The CONFIG_COREMARK_RUN_TYPE_PERFORMANCE Kconfig option - Sets CONFIG_COREMARK_DATA_SIZE to 2000 bytes.
The CONFIG_COREMARK_RUN_TYPE_PROFILE Kconfig option - Sets CONFIG_COREMARK_DATA_SIZE to 1200 bytes.
The CONFIG_COREMARK_RUN_TYPE_VALIDATION Kconfig option - Sets CONFIG_COREMARK_DATA_SIZE to 500 bytes.

You can also specify a custom CONFIG_COREMARK_DATA_SIZE value and submit your results by following the rules from the CoreMark GitHub repository. Make sure that when setting the CONFIG_COREMARK_DATA_SIZE Kconfig option the required memory space is available.

Memory allocation methods

You can select the following memory allocation methods:

The CONFIG_COREMARK_MEMORY_METHOD_STACK Kconfig option uses the main thread stack for data allocation and is enabled by default. You can change the main stack size by setting the CONFIG_MAIN_STACK_SIZE Kconfig option.
The CONFIG_COREMARK_MEMORY_METHOD_MALLOC Kconfig option uses Zephyr k_malloc() or k_free() functions to allocate the memory in the heap. You can adjust the heap size using the CONFIG_HEAP_MEM_POOL_SIZE Kconfig option.
The CONFIG_COREMARK_MEMORY_METHOD_STATIC option allows data allocation in the RAM as a regular static variable. In this case, you do not need to be aware of the main thread stack size or heap memory pool size.

Multithread mode

CoreMark can also be executed in multithread mode. To specify a number of threads, use the CONFIG_COREMARK_THREADS_NUMBER Kconfig option. In multithread mode, CoreMark is executed in all threads simultaneously. Each thread runs number of iterations equal to CONFIG_COREMARK_ITERATIONS. By default, the CONFIG_TIMESLICE_SIZE Kconfig option is set to 10 ms, which imitates RTOS multithread usage. However, in the final report, the thread execution is combined. In the multithread mode, the CONFIG_COREMARK_DATA_SIZE Kconfig option is allocated for each thread separately. Only the CONFIG_COREMARK_MEMORY_METHOD_STACK and CONFIG_COREMARK_MEMORY_METHOD_MALLOC memory methods can be used with multiple threads. In case of the CONFIG_COREMARK_MEMORY_METHOD_STACK Kconfig option, the data for all threads is allocated to the main thread stack.

Configuration options 

Check and configure the following Kconfig options:

CONFIG_APP_MODE_FLASH_AND_RUN - Start CoreMark sample automatically after flashing: If enabled, CoreMark starts execution immediately after the CPU starts up. It also disables LEDs and buttons. Otherwise, it will wait for the button to be pressed.

SB_CONFIG_APP_CPUNET_RUN - Enable execution for the network core: Enable the benchmark execution also for the network core for targets with the nRF53 Series SoCs.

Building and running 

When running the benchmark, an extra build flag (CONFIG_COMPILER_OPT) is set to -O3 to achieve the best CoreMark results.

This sample can be found under samples/benchmarks/coremark in the nRF Connect SDK folder structure.

To build the sample, you need to add the --sysbuild argument to the west build command to build and flash all the cores:

west build -b build_target --sysbuild

This way, code for all the cores will be compiled, and the west flash command will program them.

The west flash command flashes all the cores by default. If you want to flash only one core, you have to add the --domain argument:

west flash --domain hello_world

To build the sample with Visual Studio Code, follow the steps listed on the How to build an application page in the nRF Connect for VS Code extension documentation. See Configuring and building an application for other building scenarios, Programming an application for programming steps, and Testing and optimization for general information about testing and debugging in the nRF Connect SDK.

After flashing, messages describing the benchmark state will appear in the console.

Testing 

After programming the sample to your development kit, complete the following steps to test it:

Connect to the kit with a terminal emulator (for example, nRF Connect Serial Terminal). See Testing and optimization for the required settings and steps.
Reset your development kit.
To start the test, press the button assigned to the respective core. For button assignment, refer to the User interface section.

All target cores work independently from each other, and it is possible to run the benchmark on several cores simultaneously. Measurements running on a core are indicated by the corresponding LED. If the CONFIG_APP_MODE_FLASH_AND_RUN Kconfig option is enabled, the measurement will launch automatically on all available cores when starting the application. In CONFIG_APP_MODE_FLASH_AND_RUN mode LEDs and buttons are not used.
Wait for all measurements to complete. By default, the test takes approximately 11-13 seconds.

Wait for the console output for all tested cores. The results will be similar to the following example:

*** Booting Zephyr OS build bf606fc00ec1  ***
[00:00:00.502,166] <inf> app: Coremark sample for nrf52dk/nrf52832. Call address: 00007fa1
[00:00:00.502,197] <inf> app: Press Push button switch 0 to start the test ...
[00:00:14.483,764] <inf> app: Push button switch 0 pressed!
[00:00:14.511,627] <inf> app: Coremark started!
[00:00:14.511,627] <inf> app: CPU FREQ: 64000000 Hz
[00:00:14.511,627] <inf> app: (threads: 1, data size: 2000; iterations: 2000)

2K performance run parameters for coremark.
CoreMark Size    : 666
Total ticks      : 401312
Total time (secs): 12.247070
Iterations/Sec   : 163.304366
Iterations       : 2000
Compiler version : GCC10.3.0
Compiler flags   : -O3 + see compiler flags added by Zephyr
Memory location  : STACK
seedcrc          : 0xe9f5
[0]crclist       : 0xe714
[0]crcmatrix     : 0x1fd7
[0]crcstate      : 0x8e3a
[0]crcfinal      : 0x4983
Correct operation validated. See README.md for run and reporting rules.
CoreMark 1.0 : 163.304366 / GCC10.3.0 -O3 + see compiler flags added by Zephyr / STACK
[00:00:27.759,582] <inf> app: Coremark finished! Press Push button switch 0 to restart ...