gpufl 1.1.0rc2

GPU Monitoring Client

GPUFlight Client Library (gpufl)

GPUFlight Client is an open-source CUDA and ROCm/HIP profiling client for collecting GPU profiling and monitoring data from inside your application.

It records GPU workload activity such as kernel launches, GPU metrics, logical scopes, and optional low-level profiling data into local NDJSON logs. You can analyze those logs locally, generate reports, or stream them to the GPUFlight dashboard.

The goal is to make GPU profiling lighter and more continuous, closer to observability rather than only one-time profiling.

Built on CUPTI for NVIDIA GPUs and rocprofiler-sdk for AMD GPUs, GPUFlight is designed for always-on monitoring with low overhead in monitoring mode.

Project Status: 1.1.0 release candidate

GPUFlight is published to PyPI; the current release candidate is v1.1.0rc2. Breaking changes vs 1.0.x — remote_upload / HttpLogSink removed (upload moves to a post-shutdown step), and sampling_auto_start renamed to continuous_system_sampling. See CHANGELOG.md for the full migration notes. Pin an exact version if you depend on it.

To keep the initial design coherent, we are not currently accepting major feature Pull Requests. However, we welcome:

• Bug reports and local build issues.
• Documentation improvements and typo fixes.
• Feature requests and architectural suggestions via GitHub Issues.

Live Demo

Try the portal with real session data — no sign-up required:

Demo Link

Key Features

• Kernel Monitoring: Automatically intercepts all CUDA kernel launches via CUPTI.
• Production Grade: Uses a Lock-Free Ring Buffer and a Background Collector Thread to decouple logging from your hot path.
• Logical Scoping: Group thousands of micro-kernels into meaningful phases (e.g., "Inference", "PhysicsStep") using GFL_SCOPE or gpufl.Scope.
• Rich Metadata: Captures kernel names, grid/block dimensions, register counts, shared memory usage, occupancy with per-resource breakdown, and CPU stack traces.
• Profiling Engines: Choose from PC Sampling (stall analysis), SASS Metrics (instruction-level divergence), or Range Profiler (hardware counters) — one engine per session.
• System Monitoring: Collects GPU utilization, VRAM, temperature, power, and clock speeds via NVML.
• Sidecar Ready: Outputs structured NDJSON logs with automatic rotation and gzip compression.
• Deferred Upload: After a session ends, ship its NDJSON files to the GPUFlight backend with one call (gpufl.upload_logs(...)) or the orchestrated with gpufl.session(backend_url=..., api_key=...): context manager. All HTTP happens post-shutdown, so transient network failures cannot affect your GPU workload. Ideal for local dev, SSH, and Jupyter — no sidecar needed.
• Vendor Agnostic Design: Architecture ready for AMD (ROCm) support.

---

Installation

Python (PyPI)

pip install "gpufl[analyzer,viz]"

For full NVML support (GPU utilization/VRAM monitoring), build from source inside a CUDA devel container:

git clone https://github.com/gpu-flight/gpufl-client.git
CMAKE_ARGS="-DBUILD_TESTING=OFF" pip install "./gpufl-client[analyzer,viz]"

C++ (CMake FetchContent)

cmake_minimum_required(VERSION 3.31)
project(my_app LANGUAGES CXX CUDA)

include(FetchContent)
FetchContent_Declare(
    gpufl
    GIT_REPOSITORY https://github.com/gpu-flight/gpufl-client.git
    GIT_TAG        v1.1.0rc2   # pin a release tag — see the Releases page for the latest
)
FetchContent_MakeAvailable(gpufl)

add_executable(my_app main.cu)
target_link_libraries(my_app PRIVATE gpufl::gpufl CUDA::cudart CUDA::cupti)

---

Quick Start (Python + Docker)

The recommended way to get started is with a Docker container. See example/python/docker/Dockerfile for a ready-to-use Numba + Jupyter Lab playground (the published ghcr.io/gpu-flight/gpufl-jupyter:latest image).

cd example/python/docker
docker build -t gpufl-jupyter .
docker run --gpus all -p 8888:8888 -v $(pwd)/notebooks:/workspace gpufl-jupyter

import gpufl
from numba import cuda
import numpy as np

gpufl.init("my-app",
           log_path="./my_logs",
           continuous_system_sampling=True,
           enable_stack_trace=True)

@cuda.jit
def add(a, b, out):
    i = cuda.grid(1)
    if i < out.size:
        out[i] = a[i] + b[i]

n = 1 << 20
a = cuda.to_device(np.random.rand(n).astype(np.float32))
b = cuda.to_device(np.random.rand(n).astype(np.float32))
out = cuda.device_array(n, dtype=np.float32)
add[(n + 255) // 256, 256](a, b, out)
cuda.synchronize()

gpufl.shutdown()

---

Profiling Engines

CUPTI only allows one profiling mode per CUDA context at a time. Choose an engine at init:

from gpufl import ProfilingEngine

gpufl.init("my-app",
           log_path="./logs",
           profiling_engine=ProfilingEngine.PcSampling)

Engine	What it collects	Analyzer method	Best for
PcSampling	Warp stall reasons (statistical sampling)	session.inspect_stalls()	Finding why warps are stalling
SassMetrics	Per-instruction execution counts (binary instrumentation)	session.inspect_profile_samples()	Thread divergence detection
RangeProfiler	SM throughput, L1/L2 hit rates, DRAM bandwidth, tensor core %	session.inspect_perf_metrics()	Hardware counter deep-dives
None	Kernel metadata only (names, timing, occupancy)	session.inspect_hotspots()	Production monitoring with minimal overhead

C++ Usage

gpufl::InitOptions opts;
opts.app_name = "my_app";
opts.log_path = "my_logs";
opts.enable_stack_trace = true;
opts.continuous_system_sampling = true;
opts.profiling_engine = gpufl::ProfilingEngine::SassMetrics;

gpufl::init(opts);

GFL_SCOPE("training_step") {
    // your CUDA code here
}

gpufl::shutdown();

---

Talking to the Backend

gpufl writes NDJSON to disk during a session. To get those events to the GPUFlight dashboard, call gpufl.upload_logs(...) (or the orchestrated with gpufl.session(...)) after gpufl.shutdown() has returned. Every byte of HTTP traffic happens post-shutdown, so network failures cannot affect your GPU workload.

Configuration precedence

When multiple sources set the same field, higher beats lower:

4. The kwargs you pass to gpufl.init() / upload_logs()  ← highest
3. Env vars (GPUFL_BACKEND_URL, GPUFL_API_KEY, ...)
2. Local config file (config_file=...)
1. Built-in defaults                                    ← lowest

Quick start — orchestrated

import gpufl

with gpufl.session(
    app_name="my_app",
    log_path="./logs",
    backend_url="https://api.gpuflight.com",
    api_key="gpfl_xxxxxxxxxxxx",
):
    train_one_epoch()
# On __exit__: gpufl.shutdown() runs, then gpufl.upload_logs() — automatically.

Quick start — explicit

import gpufl

gpufl.init("my_app", log_path="./logs",
           backend_url="https://api.gpuflight.com",
           api_key="gpfl_xxxxxxxxxxxx")
train_one_epoch()
gpufl.shutdown()

# Ship the session you just ran (default = latest).
result = gpufl.upload_logs(
    log_path="./logs",
    backend_url="https://api.gpuflight.com",
    api_key="gpfl_xxxxxxxxxxxx",
)
if not result.success:
    for w in result.warnings:
        print(f"WARN: {w}")

CLI — gpufl upload

For post-mortem recovery or one-off ad-hoc shipping:

gpufl upload ./logs \
    --backend-url https://api.gpuflight.com \
    --api-key gpfl_xxxxxxxxxxxx

# Specific session
gpufl upload ./logs --session-id <uuid> --backend-url ... --api-key ...

# Batch every session in the dir
gpufl upload ./logs --all-sessions --backend-url ... --api-key ...

# Re-upload after the cursor marked it done
gpufl upload ./logs --force --backend-url ... --api-key ...

Env vars GPUFL_BACKEND_URL / GPUFL_API_KEY are accepted in place of the flags.

Upload mechanics

• The client writes NDJSON to disk during the session — that's the source of truth. No HTTP runs during the workload.
• gpufl.upload_logs(...) streams the files, POSTs each event to /api/v1/events/<type>, and writes a cursor file (.gpufl-upload-cursor.json) recording which sessions completed. Re-running it refuses to re-upload an already-completed session unless force=True (CLI: --force).
• Failure handling: one quick retry per POST, total 5-minute budget by default. Returns a UploadResult with .success and any .warnings — never throws on network errors.

For production fleets, the standalone gpufl-agent JVM service tails the same NDJSON files and uploads in compressed batches — it's the recommended path when many GPUs are emitting concurrently.

---

Python Analysis

The gpufl.analyzer module loads NDJSON logs and provides Rich-formatted terminal dashboards.

from gpufl.analyzer import GpuFlightSession

session = GpuFlightSession("./logs", log_prefix="my_logs")

# Executive Summary: session duration, kernel count, GPU utilization, VRAM
session.print_summary()

# Top kernels by GPU time with occupancy breakdown and stack traces
session.inspect_hotspots(top_n=5)

# Time breakdown by user-defined Scope regions
session.inspect_scopes()

# PC Sampling: per-kernel stall reason distribution
session.inspect_stalls(top_n=10)

# SASS Metrics: instruction-level execution counts and divergence
session.inspect_profile_samples(top_n=10)

# Range Profiler: SM throughput, cache hit rates, DRAM bandwidth
session.inspect_perf_metrics(top_n=10)

Visualization (Timeline)

The viz module provides interactive matplotlib plots to correlate kernel execution with system metrics.

import gpufl.viz as viz

viz.init("./logs/*.log")
viz.show()

---

Report Generation

For a quick, shareable text summary of a session — session metadata, kernel hotspots, duration percentiles, and system metrics — generate a text report. It's the fastest way to see "what happened" without opening the dashboard, and it drops cleanly into CI logs, PR comments, or a plain terminal.

The report includes:

• Session Summary — app name, session ID, duration, GPU device + SM count.
• Kernel Execution Summary — total / unique kernels, GPU-busy %, and duration statistics (avg / median / P90 / P99 / min / max). When a SASS profiling engine was active, kernel durations include instrumentation overhead and the report labels them accordingly.
• Top kernels by total GPU time — with per-kernel call counts.
• Per-kernel details — grid/block dimensions, occupancy, registers, shared memory (static + dynamic), register spills, and Waves/SM.

From C++

Call generateReport() after shutdown() — it reads the NDJSON logs written during the session:

gpufl::init(opts);
// ... your CUDA / HIP work ...
gpufl::shutdown();

gpufl::generateReport();               // print to stdout
gpufl::generateReport("report.txt");   // or save to a file

From Python

from gpufl.report import generate_report

# Print the report — wrap in print() so newlines render. In a Jupyter
# notebook this also keeps the table columns aligned (stdout renders in
# a monospace font). A bare `generate_report(...)` as a cell's last
# expression shows an escaped one-line string, so always print() it.
text = generate_report("./logs", log_prefix="my_app", top_n=10)
print(text)

# Or save it straight to a file
generate_report("./logs", log_prefix="my_app", top_n=10, output_path="report.txt")

The Python version reads the same NDJSON logs the analyzer uses — no GPU required, so you can generate reports from logs copied off another machine.

---

Testing

C++ Tests

The C++ tests use GoogleTest and are hardware-aware — NVIDIA-specific tests skip automatically if no compatible GPU is detected.

cmake --build cmake-build-debug --target gpufl_tests
ctest --test-dir cmake-build-debug --output-on-failure

Python Tests

pip install pytest
pytest tests/python/

---

Linux Configuration (Required for CUPTI)

To allow non-root users to profile GPU kernels (using CUPTI/PC Sampling) on Linux, you must relax the NVIDIA driver security restrictions. Without this, gpufl may fail to capture kernel activity.

1. Create a configuration file:

   sudo nano /etc/modprobe.d/nvidia-profiler.conf
   

2. Add the following line:

   options nvidia NVreg_RestrictProfilingToAdminUsers=0
   

3. Apply changes and reboot:

   sudo update-initramfs -u
   sudo reboot
   

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Where your logs go

By default the client writes NDJSON to disk. To stream them to a hosted dashboard, set backend_url + api_key (or the GPUFL_BACKEND_URL / GPUFL_API_KEY env vars) and they're delivered live to app.gpuflight.com. Create a workspace at gpuflight.com

This client (gpufl-client) is open source. The ingestion service and the dashboard UI are proprietary and managed-only today.