Benchmark Performance#

This document provides instructions on how to run performance benchmarks for the Vision AI applications using the provided benchmarking scripts. The script determines the maximum number of concurrent video streams a system can process (stream density) while maintaining a target performance level.

Prerequisites#

  • The edge-ai-suites repository must be cloned to your system.

  • curl, jq, gawk, ffmpeg, and bc utilities installed

Step 1: Understand the Benchmarking Script#

The core of the benchmarking process is the calc_stream_density.sh script, located in the metro-vision-ai-app-recipe/ directory. This script automates the process of starting video streams, monitoring their performance (Frames Per Second - FPS), and calculating key performance indicators (KPIs) to find the maximum sustainable stream density.

Stream Density Logic#

The script determines the maximum stream density automatically: you supply only the pipeline name and the FPS target, and the script discovers the search range itself using an exponential ramp-up followed by a bisect. Here is a summary of the logic from the calc_stream_density.sh script:

  1. Initialization: The script starts at 1 stream. It tracks the highest stream count that met the target (lo, also reported as tns) and the lowest stream count that failed it (hi). No user-provided bounds are needed.

  2. Phase 1 - Exponential ramp-up: The script measures 1, 2, 4, 8, 16, … streams. In each iteration:

    • It runs a workload with the current number of streams (ns).

    • It measures the throughput min (the lowest FPS achieved among all streams) and compares it to the target_fps.

    • If the target is met, the stream count is doubled and the search continues.

    • The first stream count that fails the target becomes the upper edge (hi) and ends this phase.

  3. Phase 2 - Bisect: The script binary-searches between the last passing count (lo) and the first failing count (hi), testing the midpoint each time and narrowing the interval, until the two are adjacent.

  4. Convergence: The final value of lo is the highest number of streams that met the performance target, reported as the final stream density. If even a single stream fails the target, the script reports that the target is not achievable. A safety ceiling (default 64 streams, override with the MAX_STREAMS environment variable) bounds the ramp-up on very capable hardware.

Average FPS Calculation#

During each test run, the script logs the avg_fps for every active pipeline instance at regular intervals. At the end of the run, an awk script processes these logs to calculate several KPIs for the collection of FPS samples from each stream:

  • Percentile Throughput: Calculates a specific percentile (e.g., 90th) of the FPS values to ignore outliers.

  • Average Throughput: The mean FPS across all streams.

  • Median Throughput: The median FPS value.

  • Cumulative Throughput: The sum of the FPS from all streams.

  • Min Throughput: The lowest (worst-case) FPS achieved among all streams. This value is critical for the stream density calculation.

NStreams Mode#

The script also supports an NStreams mode for testing fixed stream counts without binary search. This mode allows you to run multiple pipeline types in parallel simultaneously with predefined stream counts for each pipeline.

When to use NStreams Mode:

  • When you want to test specific stream count combinations across different pipelines (e.g., CPU and GPU simultaneously).

  • To measure combined workload performance of heterogeneous pipelines on the same system.

  • When you already know the desired stream counts and want to verify their performance.

How NStreams Mode Works:

  • The script starts all specified pipelines with their respective fixed stream counts concurrently.

  • Monitoring continues for the specified duration (default 60 seconds).

  • KPIs are computed for the combined workload across all pipelines.

  • No binary search is performed; results are based on the exact stream counts provided.

Step 2: Prepare for Benchmarking#

  1. Set Up and Start the Application: Before running the benchmark, you must set up and start the desired application (e.g., Loitering Detection). This ensures all services, including the DL Streamer Pipeline Server, are running and available. For setup instructions, please refer to the get-started.md guide located in the specific application’s documentation folder (e.g., Get Started for Loitering Detection).

  2. Navigate to Script Directory: Open a terminal and navigate to the metro-vision-ai-app-recipe directory.

    cd metro-ai-suite/metro-vision-ai-app-recipe/

  3. Stop Existing Pipelines: Ensure no other pipelines are running before you start the benchmark. You can stop any running pipelines with the sample_stop.sh script.

    ./sample_stop.sh

Step 3: Run the Benchmark#

Note

The default parameters are set based on best know methods recommended by Edge Workloads and Benchamarks group for workload with similar characteristics. These parameters can be modified when starting the pipelines.

The calc_stream_density.sh script requires only a pipeline name; the stream count range is determined automatically. The available pipelines are defined in the benchmark_app_payload.json file located within each application’s directory (e.g., loitering-detection/).

Example Payload with Detection and Classification

The benchmark_app_payload.json file contains an array of pipeline configurations. Each configuration specifies the pipeline name and a payload with parameters for source, destination, and AI models. The script uses the pipeline name to select the corresponding payload for benchmarking.

Here is an example of a GPU pipeline configuration that includes both detection-properties and classification-properties with additional parameters:

{
    "pipeline": "object_tracking_gpu",
    "payload": {
        "source": {
            "uri": "file:///home/pipeline-server/videos/VIRAT_S_000101_looped.mp4",
            "type": "uri"
        },
        "destination": {
            "metadata": {
                "type": "mqtt",
                "topic": "object_detection_$x",
                "publish_frame": false
            },
            "frame": {
                "type": "webrtc",
                "peer-id": "object_detection_$x",
                "overlay-properties": {
                    "font-scale": 1.0,
                    "draw-txt-bg": false
                }
            }
        },
        "parameters": {
            "detection-properties": {
                "model": "/home/pipeline-server/models/intel/pedestrian-and-vehicle-detector-adas-0001/FP16/pedestrian-and-vehicle-detector-adas-0001.xml",
                "device": "GPU",
                "inference-interval": 3,
                "inference-region": 0,
                "batch-size": 8,
                "nireq": 2,
                "ie-config": "GPU_THROUGHPUT_STREAMS=2",
                "pre-process-backend": "va-surface-sharing",
                "threshold": 0.7
            }
        }
    }
}

Example: Running Stream Density Benchmark for Loitering Detection#

This example will find the maximum number of loitering detection streams that can run on the CPU while maintaining at least 15 FPS.

  1. Execute the calc_stream_density.sh script, providing the desired pipeline name (object_tracking_cpu in this case). The script finds the stream count on its own.

    # Usage: ./calc_stream_density.sh -p <pipeline_name> -t <target_fps>

./calc_stream_density.sh -p object_tracking_cpu -t 15

  2. The script will output its progress as it tests different stream counts. The final output will show the optimal stream density found.

    ✅ FINAL RESULT: Stream-Density Benchmark Completed!
stream density: 8
======================================================

KPIs for the optimal configuration (8 streams):
throughput #1: 29.98
throughput #2: 29.98
...
throughput #8: 29.98
throughput median: 29.98
throughput average: 29.98
throughput stdev: 0
throughput cumulative: 239.84
throughput min: 29.98

Example: Running Multiple Pipelines with Fixed Stream Counts#

To test multiple pipelines in parallel with predefined stream counts (NStreams mode), use the -nstreams flag. This example runs 8 GPU streams and 6 NPU streams for loitering detection concurrently:

# Usage: ./calc_stream_density.sh -p <pipeline1> <pipeline2> ... -nstreams <count1> <count2> ...

./calc_stream_density.sh -p object_tracking_gpu object_tracking_npu -nstreams 8 6 -t 15 -i 60

Parameters:

  • -p object_tracking_gpu object_tracking_npu: Two pipeline names to run in parallel.

  • -nstreams 8 6: 8 streams for object_tracking_gpu, 6 streams for object_tracking_npu (order must match pipeline order).

  • -t 15: Target FPS threshold (optional, default 14.95).

  • -i 60: Monitoring duration in seconds (optional, default 60).

The script will start all specified pipelines and monitor their combined performance. Final output shows aggregated KPIs:

✅ FINAL RESULT: Nstreams-mode Pipeline Run Completed!
   Pipelines : object_tracking_gpu object_tracking_npu
   Streams   : 8 6
   Total     : 14 streams
======================================================

KPIs (all 14 streams combined):
throughput median: 28.5
throughput average: 28.8
...
throughput min: 27.2

Step 4: Stop the Benchmark#

After the benchmark is complete, or if you need to stop it manually, use the sample_stop.sh script. This will delete all running pipeline instances.

./sample_stop.sh

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