Configuring ArrayFire Environment {#configuring_environment}
===============================================================================

This page lists environment and runtime configurations that will help enhance
your experience with ArrayFire.

[TOC]

Environment Variables{#environment_variables}
===============================================================================

The following are useful environment variable that can be used with ArrayFire.

AF_PATH {#af_path}
-------------------------------------------------------------------------------

This is the path with ArrayFire gets installed, ie. the includes and libs are
present in this directory. You can use this variable to add include paths and
libraries to your projects.

AF_PRINT_ERRORS {#af_print_errors}
-------------------------------------------------------------------------------

When AF_PRINT_ERRORS is set to 1, the exceptions thrown are more verbose and
detailed. This helps in locating the exact failure.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
AF_PRINT_ERRORS=1 ./myprogram
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

AF_CUDA_DEFAULT_DEVICE {#af_cuda_default_device}
-------------------------------------------------------------------------------

Use this variable to set the default CUDA device. Valid values for this
variable are the device identifiers shown when af::info is run.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
AF_CUDA_DEFAULT_DEVICE=1 ./myprogram_cuda
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Note: af::setDevice call in the source code will take precedence over this
variable.

AF_OPENCL_DEFAULT_DEVICE {#af_opencl_default_device}
-------------------------------------------------------------------------------

Use this variable to set the default OpenCL device. Valid values for this
variable are the device identifiers shown when af::info is run.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
AF_OPENCL_DEFAULT_DEVICE=1 ./myprogram_opencl
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Note: af::setDevice call in the source code will take precedence over this
variable.

AF_OPENCL_DEFAULT_DEVICE_TYPE {#af_opencl_default_device_type}
-------------------------------------------------------------------------------

Use this variable to set the default OpenCL device type. Valid values for this
variable are: CPU, GPU, ACC (Accelerators).

When set, the first device of the specified type is chosen as default device.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
AF_OPENCL_DEFAULT_DEVICE_TYPE=CPU ./myprogram_opencl
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Note: `AF_OPENCL_DEFAULT_DEVICE` and af::setDevice takes precedence over this variable.

AF_OPENCL_DEVICE_TYPE {#af_opencl_device_type}
-------------------------------------------------------------------------------

Use this variable to only choose OpenCL devices of specified type. Valid values for this
variable are:

- ALL: All OpenCL devices. (Default behavior).
- CPU: CPU devices only.
- GPU: GPU devices only.
- ACC: Accelerator devices only.

When set, the remaining OpenCL device types are ignored by the OpenCL backend.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
AF_OPENCL_DEVICE_TYPE=CPU ./myprogram_opencl
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

AF_OPENCL_CPU_OFFLOAD {#af_opencl_cpu_offload}
-------------------------------------------------------------------------------

When ArrayFire runs on devices with unified memory with the host (ie.
`CL_DEVICE_HOST_UNIFIED_MENORY` is true for the device) then certain functions
are offloaded to run on the CPU using mapped buffers.

ArrayFire takes advantage of fast libraries such as MKL while spending no time
copying memory from device to host. The device memory is mapped to a host
pointer which can be used in the offloaded functions.

This functionality can be disabled by using the environment variable
`AF_OPENCL_CPU_OFFLOAD=0`.

The default bevaior of this has changed in version 3.4.

Prior to v3.4, CPU Offload functionality was used only when the user set
`AF_OPENCL_CPU_OFFLOAD=1` and disabled otherwise.

From v3.4 onwards, CPU Offload is enabled by default and is disabled only when
`AF_OPENCL_CPU_OFFLOAD=0` is set.

AF_OPENCL_SHOW_BUILD_INFO {#af_opencl_show_build_info}
-------------------------------------------------------------------------------

This variable is useful when debuggin OpenCL kernel compilation failures. When
this variable is set to 1, and an error occurs during a OpenCL kernel
compilation, then the log and kernel are printed to screen.

AF_DISABLE_GRAPHICS {#af_disable_graphics}
-------------------------------------------------------------------------------

Setting this variable to 1 will disable window creation when graphics
functions are being called. Disabling window creation will disable all other
graphics calls at runtime as well.

This is a useful enviornment variable when running code on servers and systems
without displays. When graphics calls are run on such machines, they will
print warning about window creation failing. To suppress those calls, set this
variable.

AF_SYNCHRONOUS_CALLS {#af_synchronous_calls}
-------------------------------------------------------------------------------

When this environment variable is set to 1, ArrayFire will execute all
functions synchronously.

AF_SHOW_LOAD_PATH {#af_show_load_path}
-------------------------------------------------------------------------------

When using the Unified backend, if this variable is set to 1, it will show the
path where the ArrayFire backend libraries are loaded from.

If the libraries are loaded from system paths, such as PATH or LD_LIBRARY_PATH
etc, then it will print "system path". If the libraries are loaded from other
paths, then those paths are shown in full.

AF_MEM_DEBUG {#af_mem_debug}
-------------------------------------------------------------------------------

When AF_MEM_DEBUG is set to 1 (or anything not equal to 0), the caching
mechanism in the memory manager is disabled. The device buffers are allocated
using native functions as needed and freed when going out of scope.

When the environment variable is not set, it is treated to be zero.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
AF_MEM_DEBUG=1 ./myprogram
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

AF_TRACE {#af_trace}
-------------------------------------------------------------------------------

If ArrayFire was built with logging support, this enviornment variable will
enable tracing of various modules within ArrayFire. This is a comma separated
list of modules to trace. If enabled, ArrayFire will print relevant information
to stdout. Currently the following modules are supported:

- all: All trace outputs
- jit: Logs kernel fetch & respective compile options and any errors.
- mem: Memory management allocation, free and garbage collection information
- platform: Device management information
- unified: Unified backend dynamic loading information

Tracing displays the information that could be useful when debugging or
optimizing your application. Here is how you would use this variable:

    AF_TRACE=mem,unified ./myprogram

This will print information about memory operations such as allocations,
deallocations, and garbage collection.

All trace statements printed to the console have a suffix with the following
pattern.

**[category][Seconds since Epoch][Thread Id][source file relative path] \<Message\>**

AF_MAX_BUFFERS {#af_max_buffers}
-------------------------------------------------------------------------

When AF_MAX_BUFFERS is set, this environment variable specifies the maximum
number of buffers allocated before garbage collection kicks in.

Please note that the total number of buffers that can exist simultaneously can
be higher than this number. This variable tells the garbage collector that it
should free any available buffers immediately if the treshold is reached.

When not set, the default value is 1000.

AF_OPENCL_MAX_JIT_LEN {#af_opencl_max_jit_len}
-------------------------------------------------------------------------------

When set, this environment variable specifies the maximum height of the OpenCL
JIT tree after which evaluation is forced.

The default value, as of v3.4, is 50 on OSX, 100 everywhere else. This value was
20 for older versions.

AF_CUDA_MAX_JIT_LEN {#af_cuda_max_jit_len}
-------------------------------------------------------------------------------

When set, this environment variable specifies the maximum height of the CUDA JIT
tree after which evaluation is forced.

The default value, as of v3.4, 100. This value was 20 for older versions.

AF_CPU_MAX_JIT_LEN {#af_cpu_max_jit_len}
-------------------------------------------------------------------------------

When set, this environment variable specifies the maximum length of the CPU JIT
tree after which evaluation is forced.

The default value, as of v3.4, 100. This value was 20 for older versions.

AF_BUILD_LIB_CUSTOM_PATH {#af_build_lib_custom_path}
-------------------------------------------------------------------------------

When set, this environment variable specifies a custom path along which the
symbol manager will search for dynamic (shared library) backends to load. This
is useful for specialized build configurations that use the unified backend and
build shared libraries separately.

By default, no additional path will be searched for an empty value.


AF_JIT_KERNEL_TRACE {#af_jit_kernel_trace}
-------------------------------------------------------------------------------

When set, this environment variable has to be set to one of the following
three values:

- stdout : generated kernels will be printed to standard output
- stderr : generated kernels will be printed to standard error stream
- absolute path to a folder on the disk where generated kernels will be stored

CUDA backend kernels are stored in files with cu file extension.

OpenCL backend kernels are stored in files with cl file extension.

AF_JIT_KERNEL_CACHE_DIRECTORY {#af_jit_kernel_cache_directory}
-------------------------------------------------------------------------------

This variable sets the path to the ArrayFire cache on the filesystem. If set
ArrayFire will write the kernels that are compiled at runtime to this directory.
If the path is not writeable, the default path is used.

This path is different from AF_JIT_KERNEL_TRACE which stores strings. These
kernels will store binaries and the content will be dependent on the
backend and platforms used.

The default path is determined in the following order:
  Unix:
      1. $HOME/.arrayfire
      2. /tmp/arrayfire
  Windows:
      1. ArrayFire application Temp folder(Usually
          C:\\Users\\\<user_name\>\\AppData\\Local\\Temp\\ArrayFire)
