Doca Pcc

DOCA PCC

Where to start: This skill assumes DOCA is already installed, the user's BlueField has a DPA processor that the host can see through DOCA, the BlueField firmware has the custom-PCC slot enabled, and the user is doing hands-on custom PCC work from the host side — i.e. using doca-pcc to load a DPA-side congestion control algorithm onto the BlueField, attach it to a port handling RDMA / RoCE traffic, and parameterize it from the host. Open TASKS.md if the user wants to do something (configure / build / modify / run / test / debug); open CAPABILITIES.md when the question is what can the host-side PCC API express on this version + this BlueField generation + this firmware. If the user has not installed DOCA yet, route to doca-setup first; if the user is asking how to write the DPA-side congestion-control algorithm itself (the code that runs on the DPA processor, compiled by dpacc), that is a different scope — route via doca-public-knowledge-map to the public DOCA PCC programming guide and to doca-dpa for the host-side DPA lifecycle this skill builds on. If the user only wants to inspect PCC counters at runtime without writing a custom algorithm, that is the pcc_counters CLI tool — route via doca-public-knowledge-map ## DOCA tools; this skill is for custom algorithms only.

Example questions this skill answers well

The CLASSES of PCC questions this skill is built to answer, each with one worked example. The agent should treat the class as the load-bearing piece — the worked example is a single instance.

• "How do I deploy my own custom congestion control algorithm onto a BlueField port carrying RDMA / RoCE traffic?" — worked example: "load a small DPA-side PCC algorithm and attach it to the BlueField port that handles my RoCE traffic". Answered by the two-side-program model + the host-side load-and-attach workflow in CAPABILITIES.md ## Capabilities and modes
  • the bring-up steps in TASKS.md ## configure.
• "Does this BlueField + firmware actually allow a custom PCC algorithm, and which PCC features does my DOCA install expose?" — worked example: "my host has a BlueField and the default factory PCC works; can I drop in a custom algorithm instead?". Answered by the triple-axis precondition rule (BlueField generation must carry a DPA, firmware must have the custom-PCC slot enabled, doca_pcc_cap_* against the active doca_devinfo must agree) in CAPABILITIES.md ## Capabilities and modes
  • the env-precondition checklist in TASKS.md ## configure step 1.
• "Why does my custom PCC fail with DOCA_ERROR_NOT_PERMITTED even though I have doca_dev access?" — worked example: "the BlueField firmware in this host has the custom-PCC slot disabled". Answered by the permission matrix in CAPABILITIES.md ## Safety policy
  • the firmware-side env fix in TASKS.md ## configure step 1.
• "Is this doca-pcc library the right tool for what I want, or do I want the default firmware PCC or the pcc_counters CLI?" — worked example: "I just want to read PCC counters without touching the algorithm". Answered by the path-selection rule in CAPABILITIES.md ## Capabilities and modes
  • the deferred-topic boundaries in CAPABILITIES.md ## Deferred topic boundaries which route to doca-public-knowledge-map ## DOCA tools for the counter tool.
• "Is the host-side PCC API I'm reading about on my installed DOCA?" — worked example: "is the host-side load helper I see in the docs available against the DOCA + DPACC versions on this host?". Answered by the version-compatibility overlay in CAPABILITIES.md ## Version compatibility which cross-links the canonical detection chain in doca-version and adds the PCC-specific DOCA must match DPACC overlay inherited from doca-dpa.
• "What does this DOCA_ERROR_* from a doca_pcc_* call mean and which layer caused it?" — worked example: "DOCA_ERROR_DRIVER on the host-side algorithm-load call — is it DOCA, the firmware-side custom-PCC slot, or the DPACC- produced image?". Answered by the PCC overlay on the cross-library taxonomy in CAPABILITIES.md ## Error taxonomy
  • the layered ladder in TASKS.md ## debug that escalates to doca-debug.

Audience

This skill serves external developers building applications that consume the DOCA PCC library from the host side — i.e., users whose code calls doca_pcc_* from host C / C++ to stand up the per-PCC-instance context, load a DPA-side PCC algorithm image that dpacc produced from their DPA-side source, attach it to the BlueField port that carries the RDMA / RoCE traffic the algorithm is meant to control, parameterize the algorithm, start the context, and observe runtime reports back from the algorithm. It is not for NVIDIA developers contributing to DOCA PCC itself, nor is it the place to learn how to write the DPA-side congestion-control algorithm itself (that path goes through the public DOCA PCC programming guide and the companion DOCA DPA / DPACC guides via doca-public-knowledge-map).

Language scope. DOCA PCC ships as a host-side C library with pkg-config module name doca-pcc. The host-side API is C; the DPA-side congestion-control algorithm is a separate translation unit written in the language the DPACC compiler accepts and compiled by dpacc into a binary that the host packages into the executable as the PCC algorithm image. The shipped samples under /opt/mellanox/doca/samples/doca_pcc/ are written in C plus DPA-side source (NVIDIA's choice). Other-language consumers are limited in practice — the DPA-side algorithm has no FFI escape hatch because it must be a translation unit dpacc accepts — but a Rust / Go / Python host-side wrapper that drives doca_pcc_* setup and loads a PCC algorithm image built separately is still useful, and the skill keeps the lifecycle, capability-discovery, env-precondition, and error-taxonomy guidance language-neutral.

When to load this skill

Load this skill when the user is doing hands-on DOCA PCC work from the host side for a custom congestion control algorithm, in any host language plus a DPA-side translation unit built by dpacc. Concretely:

• Initializing a doca_pcc against a doca_dev that maps to the BlueField port carrying the RDMA / RoCE traffic to be controlled.
• Loading a PCC algorithm image (doca_pcc_app) that dpacc produced from the user's DPA-side congestion-control algorithm source, into the doca_pcc context.
• Parameterizing the loaded algorithm with the host-side knobs the algorithm exposes, and starting the doca_pcc Core context so the algorithm begins affecting RDMA / RoCE traffic on the attached port.
• Checking which PCC features are supported on the active doca_devinfo via the doca_pcc_cap_* family — BlueField generations and firmware revisions differ in whether they permit a custom PCC algorithm.
• Debugging a DOCA_ERROR_* returned from a doca_pcc_* call — in particular disambiguating firmware-level custom-PCC slot disabled from device does not support custom PCC at all from algorithm image incompatible with this device from standard doca_dev access denied.
• Designing host-side bindings in a non-C language that drive a custom PCC algorithm image they built separately with dpacc — the env-precondition and capability-discovery rules in this skill still apply.

Do not load this skill for general DOCA orientation, install of DOCA or the DPACC compiler, the DPA-side programming model itself (how to write the congestion-control algorithm body that runs on the DPA), questions about the default factory PCC algorithm shipped in ConnectX firmware (no host-side doca-pcc code needed — that path is firmware-only configuration), or questions about the pcc_counters diagnostic CLI (route via doca-public-knowledge-map ## DOCA tools). For all of those, route through doca-public-knowledge-map to the matching upstream guide.

What this skill provides

This is a thin loader. The body keeps only the orientation needed to pick the right next file. The substantive PCC-specific material lives in two companion files:

• CAPABILITIES.md — what the host-side PCC API can express on this version + this BlueField generation + this firmware: the per-PCC-instance doca_pcc context, the loaded doca_pcc_app algorithm image produced by dpacc, the attach-to-port semantics that bind the algorithm to the RDMA / RoCE traffic it will control, the capability-query surface (doca_pcc_cap_*), the PCC error taxonomy mapped onto the cross-library DOCA_ERROR_* set, the observability surface (host-side reports plus the public PCC counter tool reachable via doca-public-knowledge-map), and the safety policy that gates env preconditions (DPA-capable BlueField, firmware-level custom-PCC slot enabled, matched DOCA + DPACC versions, algorithm image and host-side expectations agree).
• TASKS.md — step-by-step workflows for the six in-scope PCC verbs: configure, build, modify, run, test, debug. Plus a Deferred task verbs block that points out-of-scope questions at the right next skill.

The skill assumes a host where DOCA is already installed at the standard location, a BlueField with a DPA processor is physically present and visible to the host, the BlueField firmware has the custom-PCC slot enabled, the DPACC compiler is installed at a version matched to the DOCA install per the DOCA Compatibility Policy, and the user already knows how (at least at a sketch level) to write the DPA-side PCC algorithm that dpacc will compile. It does not cover installing DOCA, installing the DPACC compiler, or flipping firmware-level configuration — those paths go through doca-setup.