frank-default-large: threads-batch=16 confirmed optimal + decode benchmark results

Decode sweep (TB=8,16,32, 8K+ prompt, 256 gen tokens):
  TB=8:  3.3 tok/s (76.6s)
  TB=16: 3.4 tok/s (74.8s)
  TB=32: 3.4 tok/s (75.0s)

Decode is flat; TB=16 wins on prefill (5.1% faster) with zero decode tradeoff.

Also:
- Fix :: syntax error in serve-frank-large.sh
- Document systemctl disable destroys unit file; use mask/unmask instead

docs/LLM/kingjones-strix-rocmfp4.md

@@ -109,6 +109,41 @@ sized to 85% of context window:
 
 Short prompts (~3,300 tokens): 381 tok/s prompt processing, 22.7 tok/s
 generation (median of 3 runs).
+## Benchmark: threads-batch tuning
+
+Sweeped `--threads-batch` (16, 32, 48, 64, 80, 96, 128) with a 64K-token
+prompt via HTTP API (`max_tokens=1`). Fresh server start per value.
+
+| threads-batch | prefill tok/s | wall time |
+|---------------|--------------|-----------|
+| **16** | **373.5** | 62.9s |
+| 32 | 354.4 | 66.3s |
+| 48 | 344.1 | 68.3s |
+| 64 | 344.7 | 68.2s |
+| 80 | 344.4 | 68.2s |
+| 96 | 357.1 | 65.8s |
+| 128 | 321.1 | 73.2s |
+
+**Optimal: `--threads-batch 16`** (373.5 tok/s). Lower thread batching wins
+for prefill on this model -- fewer threads compete for GPU resources during
+the prompt processing phase. The default of 32 is 5.1% slower. Above 64,
+performance plateaus then declines (128 is 14% worse than optimal).
+
+## Benchmark: decode throughput
+
+Sweeped `--threads-batch` (8, 16, 32) with a ~23.5K-token code prompt and
+256 generated tokens via HTTP API. Fresh server start per value.
+
+| threads-batch | gen tokens | wall time | gen tok/s |
+|---------------|-----------|-----------|-----------|
+| 16 | 256 | 74.8s | 3.4 |
+| 32 | 256 | 75.0s | 3.4 |
+| 8 | 256 | 76.6s | 3.3 |
+
+**Decode throughput is essentially flat across all tested values.** TB=16 and
+TB=32 are identical at 3.4 tok/s; TB=8 is marginally slower at 3.3 tok/s.
+Combined with the 5.1% prefill advantage at lower thread counts, `--threads-batch
+16` is the optimal setting for both phases.
 
 ## Serving Profile
 
@@ -126,7 +161,7 @@ llama-server \
   --ctx-size 524288 --parallel 2 \
   --batch-size 4096 --ubatch-size 4096 \
   --cache-type-k f16 --cache-type-v f16 \
-  --threads 16 --threads-batch 32 \
+  --threads 16 --threads-batch 16 \
   --ctx-checkpoints 16 --cache-ram 8192 \
   --cache-prompt --cache-idle-slots --metrics \
   --temp 0.7 --top-p 0.8 --top-k 20 --min-p 0.0 \