Configuration

The underlying Legate runtime has many options for configuring the details of execution.

How to specify configuration

Legate driver

When using the legate driver, it is possible to pass most configuration options via the command line, as long as they appear before the script to run:

legate <legate options> script.py <script options>

For example to configure the CPUs and system memory per rank, you could execute:

legate --cpus 2 --sysmem 8000 script.py

It is also possible to pass these configuration options using the LEGATE_CONFIG environment variable as shown below:

LEGATE_CONFIG="--cpus 2 --sysmem 8000" legate script.py

Note

Options provided via LEGATE_CONFIG have lower precedence than arguments passed directly on the command line.

Standard Python

When invoking scripts using the standard Python interpreter, rather that the legate driver, then configuration options must be passed using the environment variable:

LEGATE_CONFIG="--cpus 2 --sysmem 8000" python script.py

Configuration scenarios

The sections below describe some of the common legate configuration options and when you might use them. For a complete list of options, exectute the command legate --help.

Resource allocation

--cpus CPUS

Number of CPUs to use per rank (default: 4)

--gpus GPUS

Number of OpenMP groups to use per rank (default: 0)

--utility UTILITY

Number of Utility processors per rank to request for meta-work (default: 2)

--sysmem SYSMEM

Amount of DRAM memory per rank (in MBs) (default: 4000)

--fbmem FBMEM

Amount of framebuffer memory per GPU (in MBs) (default: 4000)

Multi-node execution

When using the legate driver, the configuration options below can be used to launch cunumeric code for multi-node execution.

--nodes NODES

Number of nodes to use (default: 1)

--ranks-per-node RANKS_PER_NODE

Number of ranks (processes running copies of the program) to launch per node. The default (1 rank per node) will typically result in the best performance. (default: 1)

--launcher LAUNCHER

{mpirun,jsrun,srun,none} launcher program to use (set to “none” for local runs, or if the launch has already happened by the time legate is invoked), [legate-only, not supported with standard Python invocation] (default: none)

--launcher-extra LAUNCHER_EXTRA

Additional argument to pass to the launcher (can appear more than once). Multiple arguments may be provided together in a quoted string (arguments with spaces inside must be additionally quoted), [legate-only, not supported with standard Python invocation] (default: [])