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## Heatmaps & Line Graphs: GPU Utilization and Latency vs. Batch Size & Sequence Length
### Overview
The image presents a comparative analysis of GPU performance across four different GPUs: RTX3090, A100, H100, and H100 (7B). Each GPU is evaluated based on two metrics: Utilization (%) represented as a heatmap, and Latency (s) represented as a line graph. Both metrics are assessed across varying Batch Sizes (x-axis) and Sequence Lengths (y-axis). The plots are arranged in a 2x2 grid, with the heatmap above the corresponding latency graph for each GPU.
### Components/Axes
Each subplot (a-d) shares the following components:
* **Y-axis (Sequence Length):** Values are 16, 32, 64, 128, 256, 512, 1024.
* **X-axis (Batch Size):** Values are 1, 2, 4, 8, 16, 24, 32, 64, 128, 256, 512.
* **Heatmap Color Scale:** Ranges from approximately 50% (light color) to 100% (dark color), representing GPU Utilization.
* **Latency Y-axis:** Ranges from approximately 0 to 1.0 seconds.
* **Latency X-axis:** Same as the heatmap's X-axis (Batch Size).
* **Latency Line Colors/Labels (Legend - bottom right of each subplot):**
* Green: "FP16"
* Orange: "BF16"
* Blue: "FP8"
* Red: "INT8"
### Detailed Analysis or Content Details
**a) RTX3090**
* **Heatmap:** Utilization generally increases with both Batch Size and Sequence Length. The highest utilization (close to 100%) is achieved with large Batch Sizes (256+) and Sequence Lengths (128+). Lower Sequence Lengths (16, 32) show lower utilization, even with large Batch Sizes.
* (16, 1): ~54%
* (16, 512): ~66%
* (1024, 1): ~71%
* (1024, 512): ~97%
* **Latency:**
* FP16: Starts at ~0.85s (Batch Size 1), decreases to ~0.25s (Batch Size 8), then plateaus.
* BF16: Starts at ~0.80s (Batch Size 1), decreases to ~0.20s (Batch Size 8), then plateaus.
* FP8: Starts at ~0.75s (Batch Size 1), decreases to ~0.15s (Batch Size 8), then plateaus.
* INT8: Starts at ~0.70s (Batch Size 1), decreases to ~0.10s (Batch Size 8), then plateaus.
**b) A100**
* **Heatmap:** Similar trend to RTX3090, but generally higher utilization across all Batch Sizes and Sequence Lengths. Reaches 100% utilization more readily.
* (16, 1): ~74%
* (16, 512): ~85%
* (1024, 1): ~89%
* (1024, 512): ~100%
* **Latency:**
* FP16: Starts at ~0.60s (Batch Size 1), decreases to ~0.15s (Batch Size 8), then plateaus.
* BF16: Starts at ~0.55s (Batch Size 1), decreases to ~0.12s (Batch Size 8), then plateaus.
* FP8: Starts at ~0.50s (Batch Size 1), decreases to ~0.10s (Batch Size 8), then plateaus.
* INT8: Starts at ~0.45s (Batch Size 1), decreases to ~0.08s (Batch Size 8), then plateaus.
**c) H100**
* **Heatmap:** Highest utilization overall. Achieves near 100% utilization even with smaller Batch Sizes and Sequence Lengths.
* (16, 1): ~81%
* (16, 512): ~90%
* (1024, 1): ~93%
* (1024, 512): ~100%
* **Latency:**
* FP16: Starts at ~0.40s (Batch Size 1), decreases to ~0.10s (Batch Size 8), then plateaus.
* BF16: Starts at ~0.35s (Batch Size 1), decreases to ~0.08s (Batch Size 8), then plateaus.
* FP8: Starts at ~0.30s (Batch Size 1), decreases to ~0.06s (Batch Size 8), then plateaus.
* INT8: Starts at ~0.25s (Batch Size 1), decreases to ~0.05s (Batch Size 8), then plateaus.
**d) 7B's H100**
* **Heatmap:** Very similar to the standard H100, indicating minimal performance difference.
* (16, 1): ~81%
* (16, 512): ~90%
* (1024, 1): ~93%
* (1024, 512): ~100%
* **Latency:**
* FP16: Starts at ~0.40s (Batch Size 1), decreases to ~0.10s (Batch Size 8), then plateaus.
* BF16: Starts at ~0.35s (Batch Size 1), decreases to ~0.08s (Batch Size 8), then plateaus.
* FP8: Starts at ~0.30s (Batch Size 1), decreases to ~0.06s (Batch Size 8), then plateaus.
* INT8: Starts at ~0.25s (Batch Size 1), decreases to ~0.05s (Batch Size 8), then plateaus.
### Key Observations
* **GPU Performance Hierarchy:** H100 consistently outperforms A100, which outperforms RTX3090 in both utilization and latency. The 7B's H100 shows nearly identical performance to the standard H100.
* **Batch Size Impact:** Increasing Batch Size generally reduces latency across all GPUs and data types. The latency reduction is most significant at lower Batch Sizes (1-8).
* **Data Type Impact:** INT8 consistently exhibits the lowest latency, followed by FP8, BF16, and FP16.
* **Utilization Saturation:** All GPUs reach near 100% utilization with sufficiently large Batch Sizes and Sequence Lengths.
### Interpretation
The data demonstrates a clear performance scaling with GPU generation. The H100 is significantly more efficient, achieving higher utilization and lower latency compared to older GPUs like the RTX3090 and A100. The minimal difference between the H100 and 7B's H100 suggests that the 7B model does not introduce significant overhead.
The latency curves reveal the benefits of using lower precision data types (INT8, FP8) for inference. These data types reduce memory bandwidth requirements and computational complexity, leading to faster processing times. However, the latency improvements plateau at larger Batch Sizes, indicating that other factors (e.g., memory bandwidth, inter-GPU communication) become limiting.
The heatmaps show that maximizing GPU utilization is crucial for achieving optimal performance. Choosing appropriate Batch Sizes and Sequence Lengths can help ensure that the GPU is fully utilized, minimizing idle time and maximizing throughput. The data suggests that for these GPUs, larger Batch Sizes and Sequence Lengths are generally preferable, up to the point where diminishing returns are observed. The consistent trends across all GPUs suggest that these observations are generalizable and not specific to any particular hardware configuration.