doca-gpunetio-ib-write-lat

license	Apache-2.0
name	doca-gpunetio-ib-write-lat
description	Use this skill when the user is measuring GPU-kernel-initiated RDMA WRITE latency through doca-gpunetio — building and running the `gpunetio_ib_write_lat` client + server pair under `doca/tools/gpunetio_ib_write_lat/`, checking GPU-NIC pairing, reading the half-iter / full-iter / CUDA-side usec columns, characterizing median / p99 / jitter for a real-time control loop, picking GPUNetIO vs GPI vs CPU-initiated `perftest`, or weighing the latency-vs-batching trade-off. Trigger even without 'GPUNetIO' or 'ib_write_lat': 'GPU kernel RDMA latency benchmark', 'how fast can a CUDA kernel post a WRITE', 'p99 RDMA latency on H100 + ConnectX', 'kernel-launched WR tail latency', or 'compare GPU-init vs CPU-init perftest'. Route elsewhere for bandwidth runs (doca-gpunetio-ib-write-bw), the GPI surface (doca-gpi), library debugging (doca-gpunetio), or DOCA install.
metadata	{"kind":"tool"}
compatibility	Requires DOCA SDK installed at /opt/mellanox/doca on Linux (Ubuntu 22.04/24.04 or RHEL/SLES) with an InfiniBand-capable ConnectX or BlueField RNIC. Requires NVIDIA GPU with CUDA Toolkit and `nvidia_peermem` loaded; client and server hosts each need a GPU-NIC pair on a common PCIe / NVLink fabric. Reads pkg-config doca-gpunetio / doca-rdma / doca-common and builds from the source tree at /opt/mellanox/doca/tools/gpunetio_ib_write_lat against the installed DOCA.

DOCA GPUNetIO ib_write_lat

Where to start: This is a tool skill for the GPUNetIO- flavored ib_write_lat benchmark shipped under doca/tools/gpunetio_ib_write_lat/ (a client + server pair, built from source against the installed DOCA via meson). It measures the latency of an RDMA WRITE work request when the WR is posted from a CUDA kernel through the doca-gpunetio device-side surface, in a ping-pong cadence. Open TASKS.md and start at ## configure for the GPU-NIC pairing precondition and the build pattern; jump to ## run for the single-iteration smoke flow. Open CAPABILITIES.md when the question is what this tool actually measures, how it differs from the GPI sister tool on the same physical operation, or how to interpret the half-iter / full-iter / CUDA-side usec output and the median / p99 / jitter characterization. If DOCA is not installed yet, route to doca-setup first; if the user is still deciding between GPUNetIO and GPI as a programming surface, the picture in ../../libs/doca-gpunetio/CAPABILITIES.md#capabilities-and-modes and ../../libs/doca-gpi/CAPABILITIES.md#capabilities-and-modes is the first stop.

Example questions this skill answers well

The CLASSES of doca-gpunetio-ib-write-lat questions this skill is built to answer, each with one worked example. The class is the load-bearing piece; the worked example is one instance.

• "What GPU-init RDMA-WRITE latency / jitter can the GPUNetIO path deliver for a real-time / control-loop workload?" — worked example: "measure per-iteration WRITE latency between two hosts with an H100 + ConnectX-7 on each side, target the median and the p99 separately". Answered by the GPU-NIC pairing precondition in CAPABILITIES.md ## Capabilities and modes
  • the bring-up flow in TASKS.md ## configure + TASKS.md ## run.
• "This is the GPUNetIO tool — how does the latency number differ from the GPI programming surface?" — worked example: . Answered by the rule in