feat(optimize): add Phase 2 power profile and system tuning

Add `make optimize-power` (ryzenadj 85W, sysctl, THP, RADV nogttspill)
with systemd services for boot/resume persistence. Integrate into
`make optimize --all` as Phase 2. Update optimization log with RyzenAdj
results (+46% tg at 70W sustained), KV sweep data, and quant shootout.
Add Qwen3-Coder-30B and Nemotron-Cascade-2 to model catalog.

docs/optimization-log.md

@@ -37,38 +37,42 @@ Living document tracking what was applied, tested, and the actual results. Each
 
 ## Phase 2: System Tuning
 
-### 2.1 RyzenAdj 85W PPT
+### 2.1 RyzenAdj PPT Increase
 
-- **Date**: PENDING
-- **Change**: `sudo ryzenadj --stapm-limit=85000 --fast-limit=85000 --slow-limit=85000`
-- **Expected**: +12-19% CPU/GPU throughput (community data from Strix Halo Wiki)
-- **Benchmark**: Not yet run
-- **Notes**: HP ZBook ships at 60W. 85W is the community-recommended sweet spot.
-- **Verdict**: PENDING
+- **Date**: 2026-03-30
+- **Change**: `sudo ryzenadj --stapm-limit=85000 --fast-limit=85000 --slow-limit=85000 --apu-slow-limit=85000`
+- **Result**: STAPM raised from 59W→81W. PPT Fast raised to 81W. **However, PPT SLOW and APU SLOW stuck at 70W** — HP ZBook BIOS EC overrides these limits. Effective sustained power: ~70W (was ~59W).
+- **Benchmark**: `data/benchmarks/qwen35-shootout-v2-*` (Vulkan, q4_0 KV, pp2048/tg1024)
+  - UD-Q4_K_L: **57.0 t/s** (was ~39 t/s before RyzenAdj = **+46%**)
+  - UD-Q4_K_XL: **56.4 t/s**
+  - Q8_0: **51.4 t/s** (was ~39-41 t/s before = **+25%**)
+- **Thermals**: 70-73C under load, 30C headroom. Cooling handles it easily.
+- **Notes**: Settings are volatile (reset on reboot/sleep). Use `sudo make optimize-power` or install systemd service for persistence. HP firmware hard-caps slow PPT at 70W regardless.
+- **Verdict**: KEEP — significant real-world improvement despite HP firmware limit
 
 ### 2.2 VM Sysctl Tuning
 
-- **Date**: PENDING
-- **Change**: `vm.swappiness=1, vm.dirty_ratio=40, vm.max_map_count=500000`
-- **Expected**: Prevent model weight eviction, reduce I/O disruption
-- **Benchmark**: Not yet run
-- **Verdict**: PENDING
+- **Date**: 2026-03-30
+- **Change**: `vm.swappiness=1, vm.dirty_ratio=40, vm.dirty_background_ratio=10, vm.max_map_count=500000, vm.zone_reclaim_mode=0`
+- **Applied via**: `sudo make optimize-power` (persists to `/etc/sysctl.d/99-llm-inference.conf`)
+- **Notes**: Hard to isolate impact — applied together with other Phase 2 changes. Prevents model weight eviction and I/O disruption.
+- **Verdict**: KEEP — low risk, persists across reboots
 
 ### 2.3 Transparent Huge Pages
 
-- **Date**: PENDING
-- **Change**: `transparent_hugepage=always`
-- **Expected**: Faster model load time, possible 1-5% tg improvement from reduced TLB misses
-- **Benchmark**: Not yet run
-- **Verdict**: PENDING
+- **Date**: 2026-03-30
+- **Change**: `echo always > /sys/kernel/mm/transparent_hugepage/enabled`
+- **Applied via**: `sudo make optimize-power` (volatile — add `transparent_hugepage=always` to kernel cmdline for persistence)
+- **Notes**: Reduces TLB misses for mmap'd model files. Hard to isolate impact.
+- **Verdict**: KEEP — low risk
 
 ### 2.4 RADV_PERFTEST=nogttspill
 
-- **Date**: PENDING
-- **Change**: `export RADV_PERFTEST=nogttspill`
-- **Expected**: Fix pp degradation on Vulkan RADV (community-reported fix for Strix Halo)
-- **Benchmark**: Not yet run — needs Vulkan-specific benchmark comparison
-- **Verdict**: PENDING
+- **Date**: 2026-03-30
+- **Change**: `RADV_PERFTEST=nogttspill` persisted to `/etc/environment.d/radv-llm.conf`
+- **Applied via**: `sudo make optimize-power`
+- **Notes**: Prevents GTT spill management overhead on unified memory Vulkan. Takes effect on next login. For current session: `export RADV_PERFTEST=nogttspill`
+- **Verdict**: KEEP — persists across reboots
 
 ### 2.5 amdgpu.noretry=0
 
@@ -84,11 +88,19 @@ Living document tracking what was applied, tested, and the actual results. Each
 
 ### 3.1 KV Cache Quantization
 
-- **Date**: PENDING (sweep running)
-- **Change**: `-ctk q8_0 -ctv q8_0` / `-ctk q4_0 -ctv q4_0`
-- **Benchmark**: `data/benchmarks/kv-sweep-128k-*` (in progress)
-- **Expected**: Q8_0: ~50% less KV memory, negligible quality loss. Q4_0: ~75% less, noticeable quality impact.
-- **Verdict**: PENDING
+- **Date**: 2026-03-27
+- **Change**: `--kv-types f16,q8_0,q4_0` sweep
+- **Benchmark**: `data/benchmarks/kv-sweep-256k-*`
+- **Result** (Vulkan RADV, Qwen3.5-35B-A3B Q8, pp2048/tg1024):
+  - f16: 456 pp, 39.8 tg
+  - q8_0: 418 pp, 38.5 tg (slight Vulkan regression — unexpected)
+  - **q4_0: 460 pp, 41.1 tg** (fastest overall, +3% tg over f16)
+- **Result** (ROCm, same model):
+  - f16: 445 pp, 21.5 tg
+  - q8_0: 495 pp, 21.7 tg (+11% pp, same tg)
+  - q4_0: 494 pp, 21.8 tg (+11% pp, same tg)
+- **Conclusion**: q4_0 is the sweet spot on Vulkan (fastest tg + 75% less KV memory). On ROCm, KV quant helps pp but not tg.
+- **Verdict**: KEEP — use q4_0 KV as default for serving
 
 ### 3.2 MoE Batch Size `-b 256`
 
@@ -161,6 +173,24 @@ Living document tracking what was applied, tested, and the actual results. Each
 
 ---
 
+## Model Quant Shootout
+
+### Qwen3.5-35B-A3B — Q4_K_L vs Q4_K_XL vs Q8 (2026-03-30)
+
+- **Benchmark**: `data/benchmarks/qwen35-shootout-v2-*`
+- **Config**: Vulkan RADV, q4_0 KV cache, pp2048/tg1024, 2 reps
+- **RyzenAdj**: STAPM=81W (sustained ~70W due to HP firmware cap)
+
+| Quant | File Size | pp2048 (t/s) | tg1024 (t/s) | Recommendation |
+|-------|-----------|-------------|-------------|----------------|
+| UD-Q4_K_L | 18.8 GB | 825 | **57.0** | Fastest. Good quality. |
+| **UD-Q4_K_XL** | 20.7 GB | 835 | **56.4** | **Daily driver** — best quality/speed. |
+| Q8_0 | 34.4 GB | 850 | 51.4 | Best quality, 10% slower tg. |
+
+**Decision**: Keep UD-Q4_K_XL (daily driver) and Q8_0 (quality fallback). Q4_K_L can be deleted — Q4_K_XL is strictly better at only +2 GB.
+
+---
+
 ## How to Add Entries
 
 When testing a new optimization: