Environment Variables¶

MXNet have several settings that can be changed via environment variable. Usually you do not need to change these settings, but they are listed here for reference.

• MXNET_GPU_WORKER_NTHREADS (default=2)
  • Maximum number of threads that do the computation job on each GPU.
• MXNET_GPU_COPY_NTHREADS (default=1)
  • Maximum number of threads that do memory copy job on each GPU.
• MXNET_CPU_WORKER_NTHREADS (default=1)
  • Maximum number of threads that do the CPU computation job.
• MXNET_CPU_PRIORITY_NTHREADS (default=4)
  • Number of threads given to prioritized CPU jobs.
• MXNET_EXEC_ENABLE_INPLACE (default=true)
  • Whether to enable inplace optimization in symbolic execution.
• MXNET_EXEC_MATCH_RANGE (default=10)
  • The rough matching scale in symbolic execution memory allocator.
  • Set this to 0 if we do not want to enable memory sharing between graph nodes(for debug purpose).
• MXNET_EXEC_NUM_TEMP (default=1)
  • Maximum number of temp workspace we can allocate to each device.
  • Set this to small number can save GPU memory.
  • It will also likely to decrease level of parallelism, which is usually OK.
• MXNET_ENGINE_TYPE (default=ThreadedEnginePerDevice)
  • The type of underlying execution engine of MXNet.
  • List of choices
    • NaiveEngine: very simple engine that use master thread to do computation.
    • ThreadedEngine: a threaded engine that uses global thread pool to schedule jobs.
    • ThreadedEnginePerDevice: a threaded engine that allocates thread per GPU.
• MXNET_KVSTORE_REDUCTION_NTHREADS (default=4)
  • Number of threads used for summing of big arrays.
• MXNET_KVSTORE_BIGARRAY_BOUND (default=1e6)
  • The minimum size of “big array”.
  • When the array size is bigger than this threshold, MXNET_KVSTORE_REDUCTION_NTHREADS threads will be used for reduction.