Runtime Settings
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Compatibility Mode ``KVIKIO_COMPAT_MODE``
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When KvikIO is running in compatibility mode, it doesn't load ``libcufile.so``. Instead, reads and writes are done using POSIX. Notice, this is not the same as the compatibility mode in cuFile. That is cuFile can run in compatibility mode while KvikIO is not.
Set the environment variable ``KVIKIO_COMPAT_MODE`` to enable/disable compatibility mode. By default, compatibility mode is enabled:

  * when ``libcufile.so`` cannot be found.
  * when running in Windows Subsystem for Linux (WSL).
  * when ``/run/udev`` isn't readable, which typically happens when running inside a docker image not launched with ``--volume /run/udev:/run/udev:ro``.


Thread Pool ``KVIKIO_NTHREADS``
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KvikIO can use multiple threads for IO automatically. Set the environment variable ``KVIKIO_NTHREADS`` to the number of threads in the thread pool. If not set, the default value is 1.


Task Size ``KVIKIO_TASK_SIZE``
------------------------------
KvikIO splits parallel IO operations into multiple tasks. Set the environment variable ``KVIKIO_TASK_SIZE`` to the maximum task size (in bytes). If not set, the default value is 4194304 (4 MiB).


GDS Threshold ``KVIKIO_GDS_THRESHOLD``
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In order to improve performance of small IO, ``.pread()`` and ``.pwrite()`` implement a shortcut that circumvent the threadpool and use the POSIX backend directly. Set the environment variable ``KVIKIO_GDS_THRESHOLD`` to the minimum size (in bytes) to use GDS. If not set, the default value is 1048576 (1 MiB).