TornadoVM Flags

There is a number of runtime flags and compiler flags to enable experimental features, as well as fine and coarse grain profiling in the context of TornadoVM.

Note: for the following examples s0 represents an arbitrary task-graph, as well as t0 represents a given task’s name.

All flags needs Java prefix of -D. An example of tornado using a flag is the following:

$ tornado --jvm "-Dtornado.fullDebug=true" -m tornado.examples/ 1024

List of TornadoVM Flags:

  • -Dtornado.fullDebug=true:
    Enables full debugging log to be output in the. command line.
  • --printKernel:
    Print the generated OpenCL/PTX kernel in the command line.
  • --threadInfo:
    Print the information about the number of parallel threads used.
  • --debug:
    Print minor debug information such as compilation status, generated code and device information.
  • --fullDebug:
    In addition to the information dumped by the basic debug, the full debug mode also dumps information about the TornadoVM bytecode, and internal runtime status. This option is mainly used for development of TornadoVM.
  • --devices:
    Output a list of all available devices on the current system.
  • -Dtornado.ns.time=true:
    Converts the time to units to nanoseconds instead of milliseconds.
  • -Dtornado.{ptx,opencl}.priority=X: Allows to define a driver priority. The drivers are sorted in descending order based on their priority. By default, the PTX driver has priority 1 and the OpenCL driver has priority 0.

    Allows to define global worksizes (problem sizes).
  • -Ds0.t0.local.dims=XXX,XXX:
    Allows to define custom local workgroup configuration and overwrite the default values provided by the TornadoScheduler.
  • -Dtornado.profiling.enable=true:
    Enable profilling for OpenCL/CUDA events such as kernel times and data tranfers.
  • -Dtornado.opencl.userelative=true:
    Enable usage of relative addresses which is a prerequisite for using DMA tranfers on Altera/Intel FPGAs. Nonetheless, this flag can be used for any OpenCL device.
  • -Dtornado.precompiled.binary=PATH: Provides the location of the bistream or pre-generated OpenCL (.cl) kernel.

  • -Dtornado.fpga.conf.file=FILE: Provides the absolute path of the FPGA configuation file.

  • -Dtornado.fpgaDumpLog=true: Dumps the log information from the HLS compilation to the command prompt.

  • -Dtornado.opencl.blocking=true:
    Allows to force OpenCL API blocking calls.
  • --enableProfiler console:
    It enables profiler information such as COPY_IN, COPY_OUT, compilation time, total time, etc. This flag is disabled by default. TornadoVM will print by STDOUT a JSON string containing all profiler metrics related to the execution of each task-schedule.
  • --enableProfiler silent: It enables profiler information such as COPY_IN, COPY_OUT, compilation time, total time, etc. This flag is disabled by default. The profiler information is stored internally and it can be queried using the TornadoVM Profiler API.

  • --dumpProfiler FILENAME:
    It enables profiler information such as COPY_IN, COPY_OUT, compilation time, total time, etc. This flag is disabled by default. TornadoVM will save the profiler information in the FILENAME after the execution of each task-schedule.
  • -Dtornado.opencl.compiler.options=LIST_OF_OPTIONS:
    It allows to pass the compile options specified by the OpenCL CLBuildProgram specification to TornadoVM at runtime. By default it doesn’t enable any.
  • -Dtornado.concurrent.devices=true:
    Allows to run a TaskGraph in multiple devices concurrently. The user needs explicitly to define the device for each task, otherwise all tasks will run on the default device. For instance, -Ds0.t0.device=0:0 -Ds0.t1.device=0:1


  • -Dtornado.enable.fma=True:
    It enables Fused-Multiply-Add optimizations. This option is enabled by default. However, for some platforms, such as the Xilinx FPGA using SDAccel 2018.2 and OpenCL 1.0, this option must be disabled as it causes runtime errors. See issue on Github.
  • -Dtornado.enable.mathOptimizations: It enables math optimizations. For instance, 1/sqrt(x) is transformed into rsqrt instruction for the corresponding backend (OpenCL, SPIRV and PTX). It is enabled by default.

  • -Dtornado.experimental.partial.unroll=True: It enables the compiler to force partial unroll on counted loops with a factor of 2. The unroll factor can be configured with the tornado.partial.unroll.factor=FACTOR that the FACTOR value can take integer values up to 32.

  • -Dtornado.enable.nativeFunctions=False: It enables the utilization of native mathematical functions, in case that the selected backend (OpenCL, PTX, SPIR-V) supports native functions. This option is disabled by default.

Level Zero

  • -Dtornado.spirv.levelzero.alignment=64: Memory alignment (in bytes) for Level Zero buffers. It is set to 64 by default.

  • -Dtornado.spirv.levelzero.thread.dispatcher=True: If it is enabled, it uses the Level Zero suggested thread block for the thread dispatcher. True by default.

  • -Dtornado.spirv.loadstore=False: It optimizes Loads/Stores and simplifies the generated SPIR-V binary. This option is still experimental. It is set to False by default.

  • -Dtornado.spirv.levelzero.memoryAlloc.shared=False: If it is enabled, then it uses shared memory buffers between the accelerator and the host. It is set to false by default.