dcgmi nvlink#

NAME#

dcgmi-nvlink - display NVLink status and GPU error counters

SYNOPSIS#

dcgmi nvlink --errors --gpuid <gpu-id> [--json] [--host <address>]
dcgmi nvlink --link-status [--show-entity-ids] [--host <address>]

DESCRIPTION#

dcgmi nvlink reports either system-wide link state or generation-specific error fields for one GPU. Link-state output covers GPUs and NVSwitches known to the host engine. The error names and whether they are per-link or GPU-level depend on the GPU generation.

OPTIONS#

-e, --errors: Display NVLink error counters for the GPU selected by --gpuid.
-g <gpu-id>, --gpuid <gpu-id>: Select the GPU for --errors. This option is required in error mode.
-s, --link-status: Display every GPU and NVSwitch link and its current state.
--show-entity-ids: With --link-status, include the dcgm_link_t entity ID assigned to each link.
-j, --json: Use JSON for --errors output. Link-status output is text only. See JSON output.
--host <address>: Connect to the specified host engine.
-h, --help: Print generated usage information and exit.

LINK STATES AND ENTITY IDS#

--link-status prints one character per physical port:

Link-state key#
Character	State	Meaning
`U`	Up	The link is active
`D`	Down	The port is supported but the link is down
`X`	Disabled	The supported link has been disabled
`_`	Not supported	There is no supported link at that port index

With --show-entity-ids, each supported port is shown as <port>:<packed-id>. Pass that packed ID as link:<packed-id> to a command such as dcgmi dmon, or use the clearer gpu_link:<gpu>:<port> and switch_link:<switch>:<port> selectors. Not-supported _ ports have no link entity ID.

ERROR COUNTER REFERENCE#

--errors chooses its field set from the selected GPU’s architecture:

Error output by GPU generation#
Architecture	Output organization	Values
Hopper and older	One `Link <index>` section for each supported link, up to link 17	`CRC FLIT Error`, `CRC Data Error`, `Replay Error`, and `Recovery Error` totals
Blackwell and newer	One GPU-level `Error Detail` section	`Malformed Packet Error`, `Buffer Overrun Error`, `Rx Error`, `Rx Remote Error`, `Rx General Error`, `Rx Symbol Error`, `Effective Error`, `Tx Discards`, `Link Integrity Error`, `Symbol BER`, and `Effective BER`

An unsupported legacy link is omitted. A blank Blackwell value is also omitted, so absence does not mean a zero count. The operation reads current field values and does not clear them. For definitions, field IDs, aggregate versus per-link behavior, and direct dmon queries, see Compare NVLink Error Counters, Watch Traffic and Error Fields, and Field Identifiers.

EXAMPLES#

Display all link states and entity IDs:

$ dcgmi nvlink --link-status --show-entity-ids

Display error counters for GPU 0 as JSON:

$ dcgmi nvlink --errors --gpuid 0 --json