DOCA Compress

Examples

• “Offload this gzip on the BlueField.” — this is in scope if the codec is DEFLATE (or LZ4 decompress). Do not invent LZ4 encode or zstd offload.
• “Compress task returns INVALID_VALUE on alloc_init.” — size the doca_buf against the per-task cap query before changing the algorithm.

Instructions

Follow Loading order below. Open the tasks companion for configure / test / debug. Open the capabilities companion for codec support and buffer-size policy. Do not open every companion file.

Where to start: This skill assumes DOCA is already installed and the user is doing hands-on Compress work (bulk DEFLATE compression or decompression) on a BlueField / ConnectX / host with DOCA. Open the tasks companion if the user wants to do something (configure / build / modify / run / test / debug); open the capabilities companion when the question is what can DOCA Compress express on this version. If the user has not installed DOCA yet, route to doca-setup/SKILL.md first. If the user is asking “should I even offload this compression to the accelerator?”, the size-threshold path-selection rule in

Capabilities and modes

is the first stop — bulk compress is the canonical fit, tiny one-shot is not.

Example questions this skill answers well

The CLASSES of DOCA Compress 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.

• “Should I offload this compression to DOCA Compress, or just zlib/zstd on the CPU?” — worked example: “I am compressing a 4 MiB log buffer before writing it to storage; is doca-compress worth the setup vs zlib on the CPU?”. Answered by the size-threshold path-selection rule in

  Capabilities and modes

  • the “when NOT to use doca-compress” bullets in

    Safety policy.

• “Does my device support the compress (or decompress) task I want, and how big a buffer can it move per submission?” — worked example: “is doca_compress_task_compress_deflate on this BlueField, and what is the max source size per task?”. Answered by the per-task capability-query rule (doca_compress_cap_task_compress_deflate_is_supported, _decompress_deflate_is_supported, the matching _get_max_buf_size queries) in

  Capabilities and modes

  • the discovery step in

    configure.

• “I just need to decompress incoming network data — is that a valid standalone use of doca-compress?” — worked example: “my client receives DEFLATE-compressed payloads and never produces any compressed output of its own”. Answered by the “decompression-only” note in

  Capabilities and modes

  task-type table + the per-task configuration matrix in

  configure step 5.

• “What permissions does the source / destination mmap need?” — worked example: “my doca_compress_task_compress_deflate returns DOCA_ERROR_NOT_PERMITTED“. Answered by the permission matrix in

  Safety policy

  • the mmap-set-permissions checklist in

    test.

• “Is this DOCA Compress API available on my installed DOCA version?” — worked example: “is doca_compress_task_decompress_deflate in the DOCA I have installed?”. Answered by the version-compatibility overlay in

  Version compatibility,

  which cross-links the canonical detection chain in doca-version/SKILL.md and adds the Compress-specific “discover per-task support, do not assume” bullets.

• “What does this DOCA_ERROR_* from a Compress call mean and which layer caused it?” — worked example: “DOCA_ERROR_INVALID_VALUE on doca_compress_task_compress_deflate_alloc_init“. Answered by the Compress overlay on the cross-library taxonomy in

  Error taxonomy

  • the layered ladder in

    debug that escalates to

    doca-debug/SKILL.md.

Audience

This skill serves external developers building applications that consume the DOCA Compress library — i.e., users whose code calls doca_compress_* (directly in C/C++, or through FFI/bindings from another language) to offload bulk DEFLATE compression or decompression onto a BlueField DPU or ConnectX accelerator. It is not for NVIDIA developers contributing to DOCA Compress itself.

Language scope. DOCA Compress ships as a C library with pkg-config module name doca-compress. The shipped samples are written in C. C and C++ consumers are the canonical case and the worked examples in the tasks companion assume that path. Other-language consumers (Rust, Go, Python, …) consume the same *.so through FFI or language-specific bindings; the skill’s contribution in that case is to keep the lifecycle, capability-discovery, permission, error-taxonomy, and compress-vs-decompress guidance language-neutral, and to route the agent to the public C ABI as the authoritative surface that any wrapper will eventually call.

When to load this skill

Load this skill when the user is doing hands-on DOCA Compress work, in any language. Concretely:

• Initializing a doca_compress context on a doca_dev and configuring at least one task type (doca_compress_task_compress_deflate and/or doca_compress_task_decompress_deflate) before doca_ctx_start().
• Choosing between the compress task and the decompress task for the user’s data flow. The two task types are independent: a consumer that only decompresses inbound DEFLATE payloads is a valid shape and does not need to enable the compress task.
• Setting permissions on doca_mmap correctly for the source buffer (DOCA_ACCESS_FLAG_LOCAL_READ_ONLY at minimum) and the destination buffer (DOCA_ACCESS_FLAG_LOCAL_READ_WRITE).
• Sizing the source buffer against the per-task doca_compress_cap_task_*_get_max_buf_size(devinfo) ceiling and the destination buffer against the worst-case output size the algorithm can produce on this input.
• Checking which task types this device’s accelerator advertises via doca_compress_cap_task_compress_deflate_is_supported and doca_compress_cap_task_decompress_deflate_is_supported against the active doca_devinfo.
• Validating against a round-trip (compress → decompress, or decompress → compare against a known DEFLATE-encoded fixture) before pushing bulk input through the accelerator.
• Deciding whether to offload at all — the size-threshold rule in ## Capabilities and modes says doca-compress is the right answer only for bulk inputs (rule of thumb: ≥ a few KiB); below that, CPU compression beats the DMA-to-accelerator round-trip.
• Debugging a DOCA_ERROR_* returned from a Compress call (lifecycle vs. buffer-sizing vs. permission vs. unsupported-task) and the task-completion event on the progress engine.
• Designing or extending non-C bindings (Rust, Go, Python, …) that wrap the Compress C ABI — for the lifecycle, permission, capability, and compress-vs-decompress rules the wrapper must honor.

Do not load this skill for general DOCA orientation, install of DOCA itself, non-DEFLATE compression libraries on CPU (use zlib / zstd / similar), or other DOCA libraries. For those, use doca-public-knowledge-map/SKILL.md.

What this skill provides

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

• the capabilities companion — what DOCA Compress can express on this version: the four task types (compress-deflate, decompress-deflate, decompress-lz4-stream, and decompress-lz4-block, each independently capability-gated), the per-task capability-query surface (doca_compress_cap_* for task support and per-submission max buffer size), the Compress error taxonomy (mapped onto the cross-library DOCA_ERROR_* set), the observability surface (per-task completion events on the progress engine), the safety policy that gates source / destination mmap permission decisions, and the size-threshold path-selection rule (when to use doca-compress versus CPU compression or doca-dma for the no-compression copy case).
• the tasks companion — step-by-step workflows for the six in-scope Compress verbs: configure, build, modify, run, test, debug. Plus a ## rollback overlay (Compress-specific five-step teardown that drains in-flight tasks before doca_ctx_stop, unregisters mmap regions in reverse-register order, and re-verifies the device path with the round-trip smoke) and the 5-phase universal debug-loop instantiation appended to ## debug. Plus a Deferred task verbs block that points out-of-scope questions at the right next skill.

The skill assumes a host or BlueField where DOCA is already installed at the standard location and the user has the privileges their public install profile expects. It does not cover installing DOCA — that path goes through doca-setup/SKILL.md.

What this skill deliberately does not ship

This skill is agent guidance, not a samples or templates bundle. To keep the boundary clean, it deliberately does not contain — and pull requests should not add:

• Pre-written DOCA Compress application source code, in any language. The verified Compress source code is the shipped C samples at /opt/mellanox/doca/samples/doca_compress/, plus the File Compression reference application linked from the public DOCA Compress guide. The agent’s job is to route the user to those files and prescribe a minimum-diff modification on them via the universal modify-a-sample workflow in doca-programming-guide/SKILL.md, layered with the Compress-specific overrides in

  modify.

• Pre-encoded DEFLATE fixtures for arbitrary inputs. The skill tells the agent to use a round-trip validation (compress → decompress and compare to the original, or decompress a known DEFLATE blob produced by a published CPU encoder like zlib) as the known-good smoke; it does not ship a fixture bank of its own.
• Standalone build manifests (meson.build, CMakeLists.txt, Cargo.toml, …) parked inside the skill. The agent constructs the build manifest in the user’s project directory against the user’s installed DOCA, where pkg-config --modversion doca-compress is the source of truth.
• A samples/, bindings/, or reference/ subtree of any kind. A mock or incomplete artifact in this skill’s tree, even one labeled “reference”, is misleading: users will read it as buildable.

Loading order

1. Read this skill first to confirm the user’s question is in scope.
2. For the Compress capability matrix, the compress / decompress task split (including decompression-only as a standalone shape), per-task capability-query rules, permission matrix, error taxonomy, observability, and safety / path-selection policy, see the capabilities companion.
3. For step-by-step workflows — configure, build, modify, run, test, debug — see the tasks companion.

Both companion files cross-link to each other, doca-version/SKILL.md for the canonical version-handling rules, and doca-public-knowledge-map/SKILL.md whenever the right answer is “look it up in the public docs or the installed package layout” rather than “Compress-specific guidance”.

Related skills

• doca-public-knowledge-map/SKILL.md — the routing table for every public DOCA documentation source and the on-disk layout of an installed DOCA package. The DOCA Compress page lives at docs.nvidia.com/doca/sdk/DOCA-Compress/; the File Compression reference application is the canonical worked example.
• doca-setup/SKILL.md — env preparation, install verification, and the I have no install yet path with the public NGC DOCA container. This skill assumes its preconditions are satisfied.
• doca-version/SKILL.md — canonical DOCA version-handling rules. This skill’s ## Version compatibility cross-links the four-way match rule and adds only the Compress-specific “discover per-task support + per-task max buffer size via cap query” overlay.
• doca-structured-tools-contract/SKILL.md — the bundle’s structured-tools precedence rule (detect / prefer / fall back / report). The Command appendix in the tasks companion honors this contract.
• doca-programming-guide/SKILL.md — general DOCA programming patterns shared by every library: the canonical pkg-config + meson build pattern, the universal modify-a-shipped-sample first-app workflow, the universal lifecycle, the cross-library DOCA_ERROR_* taxonomy, and the program-side debug order. This skill layers Compress specifics on top.
• doca-dma/SKILL.md — the right library when the data flow is a pure mmap-to-mmap copy with no compression required. This skill’s path-selection rule routes to DMA when Compress is not the answer (e.g. the user only wants to move bytes, not encode them).
• doca-debug/SKILL.md — the cross-cutting debug ladder (install / version / build / link / runtime / program / driver). Compress-specific debug (task-not-supported, source-buffer-too-large, destination-buffer-too-small) overlays on top of that ladder.

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