doca-gpunetio-ib-write-bw

DOCA GPUNetIO ib_write_bw

Examples

• "What sustained RDMA-WRITE bandwidth can GPUNetIO deliver on this GPU-NIC pair?" — this is in scope. Stay on gpunetio_ib_write_bw; do not retune a live GPI app here.
• "Where is the bottleneck — GPU occupancy, NIC issue rate, or link saturation?" — decompose throughput before changing the CUDA kernel.

Instructions

Follow Loading order below. Open the tasks companion for configure / run / debug. Open the capabilities companion for GPU-NIC pairing and observability. Do not open every companion file.

Where to start: This is a tool skill for the GPUNetIO- flavored ib_write_bw benchmark shipped under doca/tools/gpunetio_ib_write_bw/ (a client + server pair, built from source against the installed DOCA via meson). It measures sustained RDMA WRITE bandwidth when the WRs are posted from a CUDA kernel through the doca-gpunetio device-side surface, with the GPU on the data path. Open the tasks companion and start at ## configure for the GPU-NIC pairing precondition and the build pattern; jump to ## run for the smoke-before-bulk flow. Open the capabilities companion when the question is what this tool actually measures, how the result decomposes (GPU occupancy vs NIC issue rate vs link saturation), or how the result reads against the GPI sister tool and the upstream CPU-initiated perftest ib_write_bw. If DOCA is not installed yet, route to doca-setup/SKILL.md first; if the user is still deciding between the GPI and GPUNetIO programming surfaces, the picture in doca-gpunetio/SKILL.md and doca-gpi/SKILL.md is the first stop.

Example questions this skill answers well

The CLASSES of doca-gpunetio-ib-write-bw 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 sustained RDMA-WRITE bandwidth can the GPUNetIO path deliver on this GPU-NIC pair?" — worked example: "measure sustained WRITE BW between two hosts with an H100 + ConnectX-7 on each side". Answered by the GPU-NIC pairing precondition in the capabilities companion
  • the bring-up flow in the tasks companion + the tasks companion. The same shape answers "measure GPUNetIO-driven WRITE BW between a host GPU and a BlueField DPU".
• "Where is the bottleneck — GPU compute occupancy, NIC issue rate, or link saturation?" — worked example: "I see 120 Gbit/s on a 200 Gbit/s link; is the NIC saturated, am I CPU-bound on the client, or is the CUDA kernel not driving enough WRs in flight?". Answered by the throughput-decomposition rules in the capabilities companion
  • the eval-loop overlay in the tasks companion.
• "How does the result differ from the classic CPU- initiated perftest ib_write_bw?" — worked example: "my team has a CPU-initiated WRITE BW number on this same NIC; should I expect the GPUNetIO number to match or be different?". Answered by the "GPU-initiated path adds (or removes) overhead vs the CPU-initiated path" rule in the capabilities companion.
• "Is the doca-gpunetio path the right surface for my sustained-throughput workload class?" — worked example: "my application streams sensor data from GPU memory at line rate to a remote consumer". Answered by the "when GPUNetIO is the right surface vs GPI vs CPU- initiated" rule in the capabilities companion
  • the use-side decision in the tasks companion.
• "My BW number swings between runs. What do I check before quoting it?" — worked example: "three runs at the same flags gave 145, 187, and 160 Gbit/s; is the benchmark noisy or is my platform inconsistent?". Answered by the measurement-soundness rules in the capabilities companion layer 5 + the steady-state guidance in the tasks companion.
• "What version of DOCA + CUDA Toolkit do I need for this binary to build and run?" — worked example: "my install has DOCA at one semver and CUDA at another; will the ToT-shipped gpunetio_ib_write_bw even link?". Answered by the version overlay in the capabilities companion which cross-links the canonical detection chain in doca-version/SKILL.md.