Runtime Settings

Compatibility Mode KVIKIO_COMPAT_MODE

When KvikIO is running in compatibility mode, it doesn’t load 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 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.


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.


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).


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).