Runtime Configuration

At launch time, DYAD allows users to customize its behavior and make better use of the environment through various environment variables. The list of these variables is shown below.

Name	Type	Required?	Default	Description
DYAD_KVS_NAMESPACE	String	Yes	N/A	The Flux KVS namespace that DYAD will use to record or look for file information
DYAD_PATH_PRODUCER	Directory Path	Yes [1]	N/A	The producer-managed path of the application
DYAD_PATH_CONSUMER				The consumer-managed path of the application
DYAD_DTL_MODE	String	No	FLUX_RPC	Choose data transfer method among MARGO, UCX, FLUX_RPC
DYAD_MARGO_PROTO [2]	String	No	ofi+tcp	Specify network protocol when DYAD_DTL_MODE=MARGO
DYAD_PATH_RELATIVE	0 or 1	No	0	The presence of this variable in the environment indicates that DYAD treats relative paths as relative to the managed directory
DYAD_SHARED_STORAGE	0 or 1	No	0	1: only per-file access synchronization for consumer but no transfer or the overhead associated with it
DYAD_ASYNC_PUBLISH	0 or 1	No	0	Enable asynchronous metadata publishing by producers.
DYAD_SERVICE_MUX	integer >= 1	No	1	Number of Flux brokers sharing node-local storage.
DYAD_KEY_DEPTH [3]	Integer	No	3	The number of levels in Flux’s hierarchical KVS to use within DYAD’s namespace
DYAD_KEY_BINS [3]	Integer	No	1024	The maximum number of unique hash values per level in Flux’s hierarchical KVS within DYAD’s namespace.

[1]

For DYAD to do anything, at least one of DYAD_PATH_PRODUCER or DYAD_PATH_CONSUMER must be provided. Applications will still work if neither are provided, but DYAD will not do anything.

[2]

When built with the cmake option DYAD_ENABLE_MARGO_DATA=ON and run with the env variable DYAD_DTL_MODE=MARGO, DYAD_MARGO_PROTO specifies the network protocol. See the table below for example values.

[3] (1,2)

The Flux KVS supports organized categorization of data through hierarchical key structuring. DYAD leverages this capability to optimize hash lookup performance by increasing the likelihood of early search termination when no matching entry exists in the store. The search key is hashed across multiple levels using different seeds. A match is confirmed only if corresponding entries are found at all levels, with an exact key-string match at the final level.

Examples of valid values for DYAD_MARGO_PROTO:

Value	Description
ofi+tcp	Portable TCP/IP via libfabric (default)
ofi+verbs	InfiniBand via libfabric
ofi+cxi	HPE Slingshot (Cray EX) via libfabric
na+sm	Shared memory (current Margo; use sm for older)
ucx+all://	Auto; let UCX pick, safe default, often doesn’t work
ucx+tcp://	TCP/IP, portable
ucx+rc_v://	InfiniBand RC (verbs), low-latency IB
ucx+rc_mlx5://	InfiniBand RC (mlx5), Mellanox HCAs
ucx+ud_v://	InfiniBand UD (verbs), scalable IB
ucx+dc_mlx5://	InfiniBand DC (mlx5), large-scale IB (Frontier, Sierra)
ucx+cma://	Cross-Memory Attach, intra-node shared memory (Linux)
ucx+sysv://	SysV shared memory, intra-node only