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diff --git a/lib/ethosu_monitor/README.md b/lib/ethosu_monitor/README.md new file mode 100644 index 0000000..98230ef --- /dev/null +++ b/lib/ethosu_monitor/README.md @@ -0,0 +1,76 @@ +# Arm(R) Ethos(TM)-U Monitor + +Ethos-U monitor is a library that provides an example of how to extract the +values of the PMU registers on the Arm Ethos-U55 NPU during an ongoing +inference, using an arbitrary timer source to trigger interrupts at a set +interval. It implements two backends, +[EventRecorder](https://www.keil.com/pack/doc/compiler/EventRecorder/html/index.html) +and printf. An example application showing how to use Ethos-U monitor is +included. + +## Usage +When the Ethos-U monitor constructor is called, the user specifies which backend +to use, as well as the +[```EventIDs```](https://www.keil.com/pack/doc/compiler/EventRecorder/html/group__EventRecorder__Data.html#ga44fa52e2007e535753fd4ba59b84d55d) +for the EventRecorder entries. In the second step, ``configure`` is used to +configure which PMU registers that is to be recorded. A list of available PMU +registers can be found in [pmu_ethosu.h](https://git.mlplatform.org/ml/ethos-u/ethos-u-core-driver.git/tree/include/pmu_ethosu.h?h=21.05-rc3#n55) +in the core-driver repository. ```monitorSample``` is then used to record the +values of the registers on the selected backend. Lastly, ```release``` +disables the PMU. + +### Functions +| Function name | Description | +| ----------- | ----------- | +|```EthosUMonitor(eventRecordIds, backend)``` | ```eventRecordIds``` lists the [```EventIDs```](https://www.keil.com/pack/doc/compiler/EventRecorder/html/group__EventRecorder__Data.html#ga44fa52e2007e535753fd4ba59b84d55d) that will be associated with the list of PMU registers configured in ```configure``` when using ```EVENT_RECORDER``` as backend.<br /> ```backend``` describes which backend to use, and can be either ```PRINTF``` or ```EVENT_RECORDER``` | +|```configure(driver, eventIds)``` | Configures the PMU to monitor the PMU registers listed in ```eventIds```. The maximum number of PMU registers to monitor is 4.| +| ```release(driver)``` | Disables the PMU. | +|```monitorSample(driver)``` | Samples the PMU registers configured in ```configure``` and logs them using the selected backend. | + +### Example +An example on how to use Ethos-U monitor can be found in the +[baremetal](https://git.mlplatform.org/ml/ethos-u/ethos-u-core-platform.git/tree/applications/baremetal/main.cpp?id=afadfc1ccb22fee7463c0f7b4daf467dabe98534) +application in the [ethosu-core-platform](https://git.mlplatform.org/ml/ethos-u/ethos-u-core-platform.git) repository. + +The functions ```ethosu_inference_begin``` and ```ethosu_inference_end``` are +defined as weak symbols in +[ethosu_driver.c](https://git.mlplatform.org/ml/ethos-u/ethos-u-core-driver.git/tree/src/ethosu_driver.c?h=21.05-rc3#n265). + + They are called by the Ethos-U driver before and after the Ethos-U custom + operator is executed. In the + [example application](https://git.mlplatform.org/ml/ethos-u/ethos-u-core-platform.git/tree/applications/baremetal/main.cpp?id=afadfc1ccb22fee7463c0f7b4daf467dabe98534) + a timer source is configured to periodically trigger an interrupt, on which the + the configured PMU registers are sampled one by one and recorded using + [EventRecorder](https://www.keil.com/pack/doc/compiler/EventRecorder/html/index.html) + as backend. Note that the events in this example are logged from an interrupt + context which will impact the execution time. + + Below is a sequence diagram showing a simplified version of how the different + components interact. + +. + +### Output format +#### EventRecorder +For each of the configured PMU registers, an event is recorded using the +[EventRecord2](https://www.keil.com/pack/doc/compiler/EventRecorder/html/group__EventRecorder__Data.html#gab91eb760432ad0a10652a2c922db9566) +function. Each event consists of two int32-values and an id. + +In the example application, the following PMU registers are recorded: +| EventID | Value 1 | Value 2 | +| ------- | ------- | ------- | +| Id1 | ETHOSU_PMU_CYCLE | Register value | +| Id2 | ETHOSU_PMU_NPU_ACTIVE | Register value | + +```Id1``` and ```Id2``` are defined by the ```eventRecordIds``` parameter in the +constructor of Ethos-U monitor. ```Value 1``` is the PMU register number, as +represented by the [ethosu_pmu_event_type enum](https://git.mlplatform.org/ml/ethos-u/ethos-u-core-driver.git/tree/include/pmu_ethosu.h?h=21.05-rc3#n55). +```Value 2``` is the value of the PMU register when read by the +```monitorSample``` function. + +#### printf +When using +```printf``` the register values are printed on the format +```ethosu_pmu_cntr<counter_no> : <register_value>```, where ```counter_no``` is +the index (0-3) of the configured PMU register, and ```register_value``` is the +value of the PMU register. |