feat: auto-select quantization based on available VRAM (#81)

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2026-04-15 15:03:04 +00:00
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evolution/quant_selector.py Normal file
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"""Auto-select TurboQuant compression level based on available VRAM/RAM.
Detects hardware resources at startup and picks the highest quality
quantization level that fits within available memory. Supports Apple
Silicon unified memory, NVIDIA GPUs (via nvidia-smi), and CPU-only fallback.
Usage:
from evolution.quant_selector import select_quant_level
selection = select_quant_level(model_size_gb=14.0, context_length=32768)
print(selection.level) # "turbo4"
print(selection.reasoning) # "M4 Max 36GB unified: turbo4 fits 14.0GB model + ..."
print(selection.env_vars) # {"TURBO_LAYER_ADAPTIVE": "7"}
"""
import logging
import os
import platform
import subprocess
import sys
from dataclasses import dataclass, field
from pathlib import Path
from typing import Optional
logger = logging.getLogger(__name__)
# ── Quant Level Definitions ───────────────────────────────────────────────────
@dataclass
class QuantLevel:
"""A TurboQuant compression level with its memory characteristics."""
name: str # e.g. "turbo4"
bits_per_channel: float # e.g. 3.5 for turbo4
compression_ratio: float # vs uncompressed KV cache
quality_label: str # "best", "high", "balanced", "fast"
layer_adaptive: int # TURBO_LAYER_ADAPTIVE value (0-7)
kv_type: str # -ctk/-ctv flag value
min_memory_headroom_gb: float # Minimum free memory to recommend this level
description: str = ""
# Ordered from highest quality to most aggressive compression
QUANT_LEVELS = [
QuantLevel(
name="turbo4",
bits_per_channel=3.5,
compression_ratio=4.2,
quality_label="best",
layer_adaptive=7,
kv_type="turbo4",
min_memory_headroom_gb=4.0,
description="PolarQuant + QJL 4-bit. Best quality, ~4.2x KV compression."
),
QuantLevel(
name="turbo3",
bits_per_channel=2.5,
compression_ratio=6.0,
quality_label="high",
layer_adaptive=5,
kv_type="turbo3",
min_memory_headroom_gb=3.0,
description="3-bit TurboQuant. High quality, ~6x KV compression."
),
QuantLevel(
name="turbo2",
bits_per_channel=1.5,
compression_ratio=10.0,
quality_label="balanced",
layer_adaptive=3,
kv_type="turbo2",
min_memory_headroom_gb=2.0,
description="2-bit TurboQuant. Balanced, ~10x KV compression."
),
QuantLevel(
name="q4_0",
bits_per_channel=4.0,
compression_ratio=3.5,
quality_label="fast",
layer_adaptive=0,
kv_type="q4_0",
min_memory_headroom_gb=1.5,
description="Standard 4-bit quant. Fast fallback, no TurboQuant."
),
]
# ── Hardware Detection ────────────────────────────────────────────────────────
@dataclass
class HardwareInfo:
"""Detected hardware resources."""
total_memory_gb: float
available_memory_gb: float
gpu_memory_gb: Optional[float] = None
gpu_name: Optional[str] = None
is_apple_silicon: bool = False
chip_name: Optional[str] = None
cpu_cores: int = 0
detection_method: str = ""
def detect_hardware() -> HardwareInfo:
"""Detect available memory and GPU resources."""
system = platform.system()
if system == "Darwin":
return _detect_apple_silicon()
elif system == "Linux":
return _detect_linux()
else:
return _detect_generic(system)
def _detect_apple_silicon() -> HardwareInfo:
"""Detect Apple Silicon unified memory."""
info = HardwareInfo(
total_memory_gb=0,
available_memory_gb=0,
is_apple_silicon=True,
detection_method="sysctl",
)
try:
# Get total memory
result = subprocess.run(
["sysctl", "-n", "hw.memsize"],
capture_output=True, text=True, timeout=5
)
if result.returncode == 0:
info.total_memory_gb = int(result.stdout.strip()) / (1024**3)
# Get chip name
result = subprocess.run(
["sysctl", "-n", "machdep.cpu.brand_string"],
capture_output=True, text=True, timeout=5
)
if result.returncode == 0:
info.chip_name = result.stdout.strip()
# Try to get GPU name (Apple Silicon)
result = subprocess.run(
["system_profiler", "SPDisplaysDataType"],
capture_output=True, text=True, timeout=10
)
if result.returncode == 0:
for line in result.stdout.split("\n"):
if "Chipset" in line or "GPU" in line:
info.gpu_name = line.split(":")[-1].strip()
break
# Estimate available memory (vm_stat)
result = subprocess.run(
["vm_stat"],
capture_output=True, text=True, timeout=5
)
if result.returncode == 0:
page_size = 4096 # macOS default
free_pages = 0
for line in result.stdout.split("\n"):
if "Pages free:" in line:
try:
free_pages = int(line.split(":")[-1].strip().rstrip("."))
except ValueError:
pass
# Available ≈ free + some speculative (conservative: just free)
info.available_memory_gb = (free_pages * page_size) / (1024**3)
# Fallback if vm_stat parsing failed
if info.available_memory_gb < 1:
# Conservative: 70% of total
info.available_memory_gb = info.total_memory_gb * 0.70
# Apple Silicon shares memory — GPU memory = total memory
info.gpu_memory_gb = info.total_memory_gb
# Detect CPU cores
result = subprocess.run(
["sysctl", "-n", "hw.ncpu"],
capture_output=True, text=True, timeout=5
)
if result.returncode == 0:
info.cpu_cores = int(result.stdout.strip())
except Exception as e:
logger.warning(f"Apple Silicon detection failed: {e}")
# Fallback
info.total_memory_gb = 16.0
info.available_memory_gb = 12.0
info.detection_method = "fallback"
return info
def _detect_linux() -> HardwareInfo:
"""Detect Linux system with optional NVIDIA GPU."""
info = HardwareInfo(
total_memory_gb=0,
available_memory_gb=0,
detection_method="proc",
)
try:
# Read /proc/meminfo
with open("/proc/meminfo", "r") as f:
meminfo = f.read()
for line in meminfo.split("\n"):
if line.startswith("MemTotal:"):
kb = int(line.split()[1])
info.total_memory_gb = kb / (1024 * 1024)
elif line.startswith("MemAvailable:"):
kb = int(line.split()[1])
info.available_memory_gb = kb / (1024 * 1024)
# CPU cores
info.cpu_cores = os.cpu_count() or 1
# Check for NVIDIA GPU
try:
result = subprocess.run(
["nvidia-smi", "--query-gpu=name,memory.total,memory.free",
"--format=csv,noheader,nounits"],
capture_output=True, text=True, timeout=10
)
if result.returncode == 0 and result.stdout.strip():
lines = result.stdout.strip().split("\n")
if lines:
parts = lines[0].split(", ")
if len(parts) >= 3:
info.gpu_name = parts[0].strip()
info.gpu_memory_gb = float(parts[1]) / 1024 # MB to GB
gpu_free = float(parts[2]) / 1024
# Use GPU free for VRAM-based selection
info.available_memory_gb = max(info.available_memory_gb, gpu_free)
info.detection_method = "nvidia-smi"
except (FileNotFoundError, subprocess.TimeoutExpired):
pass # No NVIDIA GPU
except Exception as e:
logger.warning(f"Linux detection failed: {e}")
info.total_memory_gb = 16.0
info.available_memory_gb = 12.0
info.detection_method = "fallback"
return info
def _detect_generic(system: str) -> HardwareInfo:
"""Fallback detection for unknown systems."""
import psutil
mem = psutil.virtual_memory()
return HardwareInfo(
total_memory_gb=mem.total / (1024**3),
available_memory_gb=mem.available / (1024**3),
cpu_cores=os.cpu_count() or 1,
detection_method="psutil",
)
# ── KV Cache Memory Estimation ───────────────────────────────────────────────
def estimate_kv_cache_gb(
context_length: int,
num_layers: int = 48,
num_kv_heads: int = 8,
head_dim: int = 128,
bits_per_channel: float = 3.5,
) -> float:
"""Estimate KV cache memory for given parameters.
Formula: 2 (K+V) × layers × kv_heads × head_dim × context_length × bits/8
"""
bytes_per_element = bits_per_channel / 8.0
total_bytes = 2 * num_layers * num_kv_heads * head_dim * context_length * bytes_per_element
return total_bytes / (1024**3)
def estimate_model_memory_gb(model_size_gb: float, quant_type: str = "q4_k_m") -> float:
"""Estimate model weights memory. Returns loaded size in GB.
This is a rough estimate — actual depends on exact quant format.
"""
# Common quant ratios (vs fp16)
quant_multipliers = {
"f16": 1.0,
"q8_0": 0.5,
"q6_k": 0.42,
"q5_k_m": 0.37,
"q4_k_m": 0.32,
"q3_k_m": 0.27,
"q2_k": 0.22,
}
# model_size_gb is already quantized size
return model_size_gb
# ── Selection Logic ───────────────────────────────────────────────────────────
@dataclass
class QuantSelection:
"""Result of quantization level selection."""
level: QuantLevel
hardware: HardwareInfo
reasoning: str
total_required_gb: float
available_gb: float
headroom_gb: float
env_vars: dict = field(default_factory=dict)
server_flags: dict = field(default_factory=dict)
warnings: list = field(default_factory=list)
def select_quant_level(
model_size_gb: float = 14.0,
context_length: int = 32768,
num_layers: int = 48,
num_kv_heads: int = 8,
head_dim: int = 128,
preferred_level: Optional[str] = None,
force_cpu: bool = False,
) -> QuantSelection:
"""Select the best quantization level for available hardware.
Args:
model_size_gb: Size of the model weights in GB
context_length: Target context length
num_layers: Number of transformer layers
num_kv_heads: Number of KV attention heads
head_dim: Dimension per attention head
preferred_level: Force a specific level (still checks if it fits)
force_cpu: If True, ignore GPU memory
Returns:
QuantSelection with the chosen level and reasoning
"""
hw = detect_hardware()
if force_cpu:
hw.gpu_memory_gb = None
hw.gpu_name = None
# Use the most restrictive memory constraint
# For Apple Silicon: unified memory, use total
# For NVIDIA: use GPU VRAM
# For CPU-only: use system RAM
if hw.gpu_memory_gb and hw.gpu_name:
memory_pool_gb = hw.gpu_memory_gb
memory_label = f"{hw.gpu_name} {hw.gpu_memory_gb:.0f}GB VRAM"
elif hw.is_apple_silicon:
memory_pool_gb = hw.total_memory_gb
memory_label = f"{hw.chip_name or 'Apple Silicon'} {hw.total_memory_gb:.0f}GB unified"
else:
memory_pool_gb = hw.total_memory_gb
memory_label = f"{hw.cpu_cores}c CPU {hw.total_memory_gb:.0f}GB RAM"
model_mem = estimate_model_memory_gb(model_size_gb)
# Try levels from best to most compressed
chosen = None
for level in QUANT_LEVELS:
if preferred_level and level.name != preferred_level:
continue
kv_mem = estimate_kv_cache_gb(
context_length, num_layers, num_kv_heads, head_dim,
level.bits_per_channel
)
total_required = model_mem + kv_mem
headroom = memory_pool_gb - total_required
if headroom >= level.min_memory_headroom_gb:
chosen = level
break
if preferred_level and level.name == preferred_level:
# User forced this level but it doesn't fit
chosen = level
break
if chosen is None:
# Nothing fits — pick the most aggressive compression
chosen = QUANT_LEVELS[-1]
logger.warning(f"No quant level fits in {memory_pool_gb:.1f}GB. Using {chosen.name}.")
# Calculate final numbers
kv_mem = estimate_kv_cache_gb(
context_length, num_layers, num_kv_heads, head_dim,
chosen.bits_per_channel
)
total_required = model_mem + kv_mem
headroom = memory_pool_gb - total_required
# Build reasoning
reasoning_parts = [
f"{memory_label}:",
f"{chosen.name} ({chosen.quality_label}, {chosen.bits_per_channel:.1f}b/ch,",
f"{chosen.compression_ratio:.1f}x compression)",
f"fits {model_mem:.1f}GB model + {kv_mem:.1f}GB KV cache",
f"@ {context_length}K context = {total_required:.1f}GB / {memory_pool_gb:.0f}GB",
f"({headroom:.1f}GB headroom)"
]
reasoning = " ".join(reasoning_parts)
# Build environment variables for llama.cpp
env_vars = {
"TURBO_LAYER_ADAPTIVE": str(chosen.layer_adaptive),
}
# Build server flags
server_flags = {
"-ctk": chosen.kv_type,
"-ctv": chosen.kv_type,
"-c": str(context_length),
}
# Warnings
warnings = []
if headroom < 2.0:
warnings.append(
f"Low headroom ({headroom:.1f}GB). Consider reducing context length or model size."
)
if headroom < 0:
warnings.append(
f"OVERCOMMITTED: needs {total_required:.1f}GB but only {memory_pool_gb:.0f}GB available. "
f"Inference may fail or swap heavily."
)
selection = QuantSelection(
level=chosen,
hardware=hw,
reasoning=reasoning,
total_required_gb=total_required,
available_gb=memory_pool_gb,
headroom_gb=headroom,
env_vars=env_vars,
server_flags=server_flags,
warnings=warnings,
)
logger.info(f"Quant selection: {reasoning}")
for w in warnings:
logger.warning(w)
return selection
# ── CLI ───────────────────────────────────────────────────────────────────────
def main():
"""CLI entry point for quant level selection."""
import argparse
import json
parser = argparse.ArgumentParser(
description="Auto-select TurboQuant compression level based on available hardware"
)
parser.add_argument("--model-size", type=float, default=14.0,
help="Model size in GB (default: 14.0)")
parser.add_argument("--context", type=int, default=32768,
help="Target context length (default: 32768)")
parser.add_argument("--layers", type=int, default=48,
help="Number of transformer layers (default: 48)")
parser.add_argument("--kv-heads", type=int, default=8,
help="Number of KV attention heads (default: 8)")
parser.add_argument("--head-dim", type=int, default=128,
help="Dimension per attention head (default: 128)")
parser.add_argument("--prefer", type=str, default=None,
choices=[l.name for l in QUANT_LEVELS],
help="Prefer a specific quant level")
parser.add_argument("--force-cpu", action="store_true",
help="Ignore GPU, use CPU memory only")
parser.add_argument("--json", action="store_true",
help="JSON output for automation")
parser.add_argument("--detect-only", action="store_true",
help="Only detect hardware, don't select")
args = parser.parse_args()
logging.basicConfig(level=logging.INFO, format="%(message)s")
if args.detect_only:
hw = detect_hardware()
if args.json:
print(json.dumps(hw.__dict__, default=str, indent=2))
else:
print(f"Total memory: {hw.total_memory_gb:.1f} GB")
print(f"Available: {hw.available_memory_gb:.1f} GB")
if hw.gpu_memory_gb:
print(f"GPU memory: {hw.gpu_memory_gb:.1f} GB")
if hw.gpu_name:
print(f"GPU: {hw.gpu_name}")
if hw.is_apple_silicon:
print(f"Chip: {hw.chip_name or 'Apple Silicon'}")
print(f"CPU cores: {hw.cpu_cores}")
print(f"Detection: {hw.detection_method}")
return
selection = select_quant_level(
model_size_gb=args.model_size,
context_length=args.context,
num_layers=args.layers,
num_kv_heads=args.kv_heads,
head_dim=args.head_dim,
preferred_level=args.prefer,
force_cpu=args.force_cpu,
)
if args.json:
result = {
"level": selection.level.name,
"bits_per_channel": selection.level.bits_per_channel,
"compression_ratio": selection.level.compression_ratio,
"quality": selection.level.quality_label,
"reasoning": selection.reasoning,
"total_required_gb": round(selection.total_required_gb, 2),
"available_gb": round(selection.available_gb, 1),
"headroom_gb": round(selection.headroom_gb, 2),
"env_vars": selection.env_vars,
"server_flags": selection.server_flags,
"warnings": selection.warnings,
"hardware": {
"total_memory_gb": round(selection.hardware.total_memory_gb, 1),
"gpu_name": selection.hardware.gpu_name,
"is_apple_silicon": selection.hardware.is_apple_silicon,
"chip_name": selection.hardware.chip_name,
"cpu_cores": selection.hardware.cpu_cores,
},
}
print(json.dumps(result, indent=2))
else:
print(f"Selected: {selection.level.name} ({selection.level.quality_label})")
print(f" {selection.reasoning}")
print()
print(f"Environment variables:")
for k, v in selection.env_vars.items():
print(f" export {k}={v}")
print()
print(f"Server flags:")
for k, v in selection.server_flags.items():
print(f" {k} {v}")
if selection.warnings:
print()
for w in selection.warnings:
print(f" WARNING: {w}")
if __name__ == "__main__":
main()