rocm-systems/source/docs/how-to/using-rocprofiler-sdk-roctx.rst

.. meta::
  :description: Documentation for the usage of rocprofiler-sdk-roctx library
  :keywords: ROCprofiler-SDK tool, using-rocprofiler-sdk-roctx library, roctx, markers, ranges, rocprofv3, rocprofv3 tool usage, Using rocprofv3, ROCprofiler-SDK command line tool, marker-trace

.. _using-rocprofiler-sdk-roctx:

============
Using ROCTx
============

ROCTx is AMD tools extension library, a cross platform API for annotating code with markers and ranges. The ROCTx API is written in C++.
In certain situations, such as debugging performance issues in large-scale GPU programs, API-level tracing might be too fine-grained to provide a big picture of the program execution.
In such cases, it is helpful to define specific tasks to be traced. To specify the tasks for tracing, enclose the respective source code with the API calls provided by the ROCTx library.
This process is also known as instrumentation.

ROCTx annotations
++++++++++++++++++

ROCTx provides two types of annotations: markers and ranges.

Markers
========

Markers are used to insert a marker in the code with a message. Creating markers help you see when a line of code is executed.

Ranges
=======

Ranges are used to define the scope of code for instrumentation using enclosing API calls.
A range is a programmer-defined task that has a well-defined start and end code scope.
You can also refine the scope specified within a range using further nested ranges. ``rocprofv3`` also reports the timelines for these nested ranges.

These are the two types of ranges:

- **Push and Pop:** These can be nested to form a stack. The Pop call is automatically associated with a prior Push call on the same thread.

- **Start and End:** These may overlap with other ranges arbitrarily. The Start call returns a handle that must be passed to the End call. These ranges can start and end on different threads.

ROCTx APIs
===========

Here is the list of useful APIs for code instrumentation:

- ``roctxMark``: Inserts a marker in the code with a message. Creating marks help you see when a line of code is executed.
- ``roctxRangeStart``: Starts a range. Different threads can start ranges.
- ``roctxRangePush``: Starts a new nested range.
- ``roctxRangePop``: Stops the current nested range.
- ``roctxRangeStop``: Stops the given range.
- ``roctxProfilerPause``: Requests any currently running profiling tool to stop data collection.
- ``roctxProfilerResume``: Requests any currently running profiling tool to resume data collection.
- ``roctxGetThreadId``: Retrieves the ID for the current thread identical to the ID received using ``rocprofiler_get_thread_id(rocprofiler_thread_id_t*)``.
- ``roctxNameOsThread``: Labels the current CPU OS thread in the profiling tool output with the provided name.
- ``roctxNameHsaAgent``: Labels the given HSA agent in the profiling tool output with the provided name.
- ``roctxNameHipDevice``: Labels the HIP device ID in the profiling tool output with the provided name.
- ``roctxNameHipStream``: Labels the given HIP stream in the profiling tool output with the provided name.

Using ROCTx in the application
+++++++++++++++++++++++++++++++

The following sample code from the MatrixTranspose application shows the usage of ROCTx APIs:

.. code-block:: bash

    #include <rocprofiler-sdk-roctx/roctx.h>

    roctxMark("before hipLaunchKernel");
    int rangeId = roctxRangeStart("hipLaunchKernel range");
    roctxRangePush("hipLaunchKernel");

    // Launching kernel from host
    hipLaunchKernelGGL(matrixTranspose, dim3(WIDTH/THREADS_PER_BLOCK_X, WIDTH/THREADS_PER_BLOCK_Y), dim3(THREADS_PER_BLOCK_X, THREADS_PER_BLOCK_Y), 0,0,gpuTransposeMatrix,gpuMatrix, WIDTH);

    roctxMark("after hipLaunchKernel");

    // Memory transfer from device to host
    roctxRangePush("hipMemcpy");

    hipMemcpy(TransposeMatrix, gpuTransposeMatrix, NUM * sizeof(float), hipMemcpyDeviceToHost);

    roctxRangePop();  // for "hipMemcpy"
    roctxRangePop();  // for "hipLaunchKernel"
    roctxRangeStop(rangeId);

To trace the API calls enclosed within the range, use:

.. code-block:: bash

    rocprofv3 --marker-trace -- <application_path>

Running the preceding command generates a ``marker_api_trace.csv`` file prefixed with the process ID.

.. code-block:: shell

    $ cat 210_marker_api_trace.csv

Here are the contents of ``marker_api_trace.csv`` file:

.. csv-table:: Marker api trace
   :file: /data/marker_api_trace.csv
   :widths: 10,10,10,10,10,20,20
   :header-rows: 1

For the description of the fields in the output file, see :ref:`output-file-fields`.

``roctxProfilerPause`` and ``roctxProfilerResume`` can be used to hide the calls between them. This is useful when you want to hide the calls that are not relevant to your profiling session.

.. code-block:: bash

    #include <rocprofiler-sdk-roctx/roctx.h>

    // Memory transfer from host to device
    HIP_API_CALL(hipMemcpy(gpuMatrix, Matrix, NUM * sizeof(float), hipMemcpyHostToDevice));

    auto tid = roctx_thread_id_t{};
    roctxGetThreadId(&tid);
    roctxProfilerPause(tid);
    // Memory transfer that should be hidden by profiling tool
    HIP_API_CALL(
        hipMemcpy(gpuTransposeMatrix, gpuMatrix, NUM * sizeof(float), hipMemcpyDeviceToDevice));
    roctxProfilerResume(tid);

    // Launching kernel from host
    hipLaunchKernelGGL(matrixTranspose,
                       dim3(WIDTH / THREADS_PER_BLOCK_X, WIDTH / THREADS_PER_BLOCK_Y),
                       dim3(THREADS_PER_BLOCK_X, THREADS_PER_BLOCK_Y),
                       0,
                       0,
                       gpuTransposeMatrix,
                       gpuMatrix,
                       WIDTH);

    // Memory transfer from device to host
    HIP_API_CALL(
        hipMemcpy(TransposeMatrix, gpuTransposeMatrix, NUM * sizeof(float), hipMemcpyDeviceToHost));

To trace the preceding code, use:

.. code-block:: shell

    rocprofv3 --marker-trace --hip-trace -- <application_path>

The preceding command generates a ``hip_api_trace.csv`` file prefixed with the process ID. The file has only two ``hipMemcpy`` calls with the in-between ``hipMemcpyDeviceToHost`` hidden .

.. code-block:: shell

   "Domain","Function","Process_Id","Thread_Id","Correlation_Id","Start_Timestamp","End_Timestamp"
   "HIP_COMPILER_API","__hipRegisterFatBinary",1643920,1643920,1,320301257609216,320301257636427
   "HIP_COMPILER_API","__hipRegisterFunction",1643920,1643920,2,320301257650707,320301257678857
   "HIP_RUNTIME_API","hipGetDevicePropertiesR0600",1643920,1643920,4,320301258114239,320301337764472
   "HIP_RUNTIME_API","hipMalloc",1643920,1643920,5,320301338073823,320301338247374
   "HIP_RUNTIME_API","hipMalloc",1643920,1643920,6,320301338248284,320301338399595
   "HIP_RUNTIME_API","hipMemcpy",1643920,1643920,7,320301338410995,320301631549262
   "HIP_COMPILER_API","__hipPushCallConfiguration",1643920,1643920,10,320301632131175,320301632134215
   "HIP_COMPILER_API","__hipPopCallConfiguration",1643920,1643920,11,320301632137745,320301632139735
   "HIP_RUNTIME_API","hipLaunchKernel",1643920,1643920,12,320301632142615,320301632898289
   "HIP_RUNTIME_API","hipMemcpy",1643920,1643920,14,320301632901249,320301633934395
   "HIP_RUNTIME_API","hipFree",1643920,1643920,15,320301643320908,320301643511479
   "HIP_RUNTIME_API","hipFree",1643920,1643920,16,320301643512629,320301643585639

Resource naming
++++++++++++++++

``ROCTx`` provides APIs to rename certain resources in the output generated by the profiling tool. You can pass the desired label for a specific resource in the output as an argument to the API. Note that ROCprofiler-SDK doesn't provide any explicit support for how profiling tools handle this request. Support for this capability is tool-specific.

The following table lists the APIs available for labeling the given resources:

.. |br| raw:: html

    <br />

.. list-table:: resource naming
    :header-rows: 1

    * - Resource
      - API
      - Description

    * - OS thread
      - ``roctxNameOsThread(const char* name)``
      - Labels the current CPU OS thread with the given name in the output. Note that ROCTx does NOT rename the thread using ``pthread_setname_np``.

    * - HIP runtime
      - | ``roctxNameHipDevice(const char* name, int device_id)`` |br| |br|
        | ``roctxNameHipStream(const char* name, const struct ihipStream_t* stream)``
      - | Labels the given HIP device ID with the given name in the output. |br| |br|
        | Labels the given HIP stream ID with the given name in the output.

    * - HSA runtime
      - ``roctxNameHsaAgent(const char* name, const struct hsa_agent_s*)``
      - Labels the given HSA agent with the given name in the output.