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strata_bench.py records a layer-split run as single-GPU (card list and VRAM total)

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Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
91/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Active
Tech stack
python
Domain
devtools, testing

Research direction

Start at tools/strata_bench.py:614-616 and inspect how static["gpu_name"] is matched against the locally used cards. Reproduce with the described two-GPU layer-split configuration and ./bench.sh --url http://127.0.0.1:<port>. Done means the generated README.md and results.json retain both served GPU names and report the combined 40952 MiB, while single-card cases remain unchanged.

Written by the indexing model from the issue text.

Description

What happened

A benchmark of a two-card layer split (RTX 3090 + RTX 4080 SUPER) produces a report naming only the first card:

"gpu": ["NVIDIA GeForce RTX 3090"], "gpu_vram_mib": 24576

while the server reports both correctly:

"machine": {"gpu": {"name": "NVIDIA GeForce RTX 3090 + NVIDIA GeForce RTX 4080 SUPER",
                    "total_mib": 40952}}

and the engine log says layer split: layers 0-28 (CUDA0), 29-47 (CUDA1), one hand-off per window.

Cause, tools/strata_bench.py:614-616:

elif len(used) > 1 and static.get("gpu_name"):
    named = [g for g in used if g["name"] == static["gpu_name"]]
    used = named[:1] or used[:1]

With a split, static["gpu_name"] is "A + B", so no single card equals it, named is empty, and used is truncated to the first card. gpu_vram_mib is then summed over that one card (lines 627-628), overriding the server's correct total. The " + " form is already parsed 20 lines below (#2001), but that branch only fires when the served cards are not all local (the other-vendor case), so a split across two local NVIDIA cards never reaches it.

The branch is only reached when cfg is None, i.e. with --url. On current main that is the only way to benchmark at all, because bench.sh crashes when it starts the server itself (#2872). So at the moment every layer-split run benchmarked with the tool is reported as single-GPU, in both the card list and the VRAM total.

To reproduce: a config with "gpu": [0, 1], start the server, then ./bench.sh --url http://127.0.0.1:<port>. The generated README.md and results.json name one card.

Suggested fix: match each name the server gives, keeping the count.

elif len(used) > 1 and static.get("gpu_name"):
    served_names = [n for n in static["gpu_name"].split(" + ") if n and n != "?"]
    named = [g for g in used if g["name"] in served_names]
    used = named[:len(served_names)] or used[:1]

Checked against this machine's values: the split case becomes ["RTX 3090", "RTX 4080 SUPER"] / 40952 MiB, and both single-card-of-two cases are unchanged.

Strata version, GPU, OS

Engine 0.1.45, main at 477ac13c (these lines unchanged on main today). RTX 3090 + RTX 4080 SUPER, Linux (Ubuntu 24.04 base), engine compiled from source.

Dominant language
C++
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