chore: import upstream snapshot with attribution
This commit is contained in:
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#!/usr/bin/env python3
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"""
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SplitLinear: Drop-in replacement for nn.Linear / nn.QuantizedLinear.
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Splits GEMM along output channels — ANE does ~65%, GPU does ~35%, concurrent.
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Key optimization: same-input projections (Q/K/V, Gate/Up) share a single
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input preparation via _InputGroup, eliminating redundant transpose+eval+numpy.
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Usage:
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from split_linear import patch_model
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bridge = patch_model(model, seq=512)
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API:
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patch_model(model, seq) → high-level one-liner
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SplitLinear(layer, bridge, seq) → single layer replacement
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ANEBridge() → ANE private API wrapper
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"""
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import os, ctypes
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from concurrent.futures import ThreadPoolExecutor
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import numpy as np
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import mlx.core as mx
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import mlx.nn as nn
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LIB_DIR = os.path.dirname(os.path.abspath(__file__))
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SPLIT_ALIGN = 64
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MIN_SEQ_FOR_SPLIT = 192 # Below this, split overhead > benefit
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# ─── ANE Bridge ───
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class ANEBridge:
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"""Thin wrapper around ANE private API."""
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_instance = None
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def __init__(self):
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lib = ctypes.CDLL(os.path.join(LIB_DIR, 'libane_bridge_v6.dylib'))
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lib.ane_init.restype = ctypes.c_int
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lib.ane_load_model.restype = ctypes.c_int
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lib.ane_load_model.argtypes = [ctypes.c_int, ctypes.c_int, ctypes.c_int,
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ctypes.POINTER(ctypes.c_float)]
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lib.ane_run.restype = ctypes.c_int
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lib.ane_run.argtypes = [ctypes.c_int, ctypes.POINTER(ctypes.c_float),
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ctypes.POINTER(ctypes.c_float)]
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lib.ane_run_rowmajor.restype = ctypes.c_int
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lib.ane_run_rowmajor.argtypes = [ctypes.c_int, ctypes.POINTER(ctypes.c_float),
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ctypes.c_int, ctypes.POINTER(ctypes.c_float)]
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lib.ane_model_count.restype = ctypes.c_int
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lib.ane_surface_count.restype = ctypes.c_int
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assert lib.ane_init() == 0, "ANE init failed"
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self.lib = lib
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def load(self, ic, oc, seq, w_fp32):
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w = np.ascontiguousarray(w_fp32, dtype=np.float32)
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h = self.lib.ane_load_model(ic, oc, seq,
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w.ctypes.data_as(ctypes.POINTER(ctypes.c_float)))
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assert h >= 0, f"ANE load failed: {ic}→{oc}, seq={seq}"
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return h
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def run(self, h, inp, out):
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self.lib.ane_run(h,
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inp.ctypes.data_as(ctypes.POINTER(ctypes.c_float)),
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out.ctypes.data_as(ctypes.POINTER(ctypes.c_float)))
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def run_rowmajor(self, h, inp_rm, L, out_rm):
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"""ANE compute with row-major I/O. Uses vDSP for transpose.
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inp_rm: [L, IC] row-major float32
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out_rm: [L, OC] row-major float32 (pre-allocated)
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"""
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self.lib.ane_run_rowmajor(h,
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inp_rm.ctypes.data_as(ctypes.POINTER(ctypes.c_float)),
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L,
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out_rm.ctypes.data_as(ctypes.POINTER(ctypes.c_float)))
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@property
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def model_count(self):
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return self.lib.ane_model_count()
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@classmethod
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def shared(cls):
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if cls._instance is None:
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cls._instance = cls()
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return cls._instance
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# Single ANE worker thread
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_ane_pool = ThreadPoolExecutor(max_workers=1, thread_name_prefix='ane')
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# ─── Helpers ───
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def _extract_weight(layer):
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"""Extract FP32 weight [OC, IC] from nn.Linear or nn.QuantizedLinear."""
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if isinstance(layer, nn.QuantizedLinear):
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mx.eval(layer.weight, layer.scales)
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b = getattr(layer, 'biases', None)
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if b is not None:
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mx.eval(b)
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w = mx.dequantize(layer.weight, layer.scales, b,
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layer.group_size, layer.bits)
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else:
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w = layer.weight
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mx.eval(w)
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return np.array(w, dtype=np.float32)
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class _InputGroup:
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"""
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Shared input preparation for same-input projections (Q/K/V or Gate/Up).
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Zero-copy path: eval x as FP32 row-major, share numpy view across group.
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No GPU transpose needed — ane_run_rowmajor handles transpose in C via vDSP.
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"""
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__slots__ = ('_np', '_x2d', '_L', '_seq')
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def __init__(self, ic=0, seq=0):
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self._np = None
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self._x2d = None
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self._L = 0
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self._seq = seq
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def prepare(self, x):
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"""Prepare input. Called by first proj in group.
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Returns (inp_np_rowmajor [L, IC], x_2d, L)."""
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x_2d = x.reshape(-1, x.shape[-1]) if x.ndim == 3 else x
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L = x_2d.shape[0]
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# Cast to FP32 contiguous row-major, eval, then zero-copy numpy view
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x_f32 = x_2d.astype(mx.float32) if x_2d.dtype != mx.float32 else x_2d
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x_f32 = mx.contiguous(x_f32)
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mx.eval(x_f32)
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self._np = np.array(x_f32, copy=False) # [L, IC] row-major, zero-copy
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self._L = L
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self._x2d = x_2d
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return self._np, x_2d, L
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def get(self):
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"""Get cached input. Called by subsequent projs.
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Returns (inp_np_rowmajor [L, IC], x_2d, L)."""
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return self._np, self._x2d, self._L
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# ─── SplitLinear ───
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class SplitLinear:
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"""
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Drop-in nn.Linear replacement with ANE+GPU tensor parallelism.
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Two modes controlled externally via set_prefill(True/False):
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- prefill: ANE ~65% + GPU ~35% concurrent
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- decode: original nn.Linear on GPU → zero overhead
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"""
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_prefill_mode = False # class-level flag
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def __init__(self, layer, bridge, seq, ane_frac=None, name="",
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input_group=None, is_first=True):
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self.name = name
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self._orig = layer # always keep original for decode
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w_np = _extract_weight(layer)
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oc, ic = w_np.shape
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self.ic = ic
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self.oc = oc
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self.seq = seq
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self._is_first = is_first
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# Auto-detect split fraction
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if ane_frac is None:
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if seq < MIN_SEQ_FOR_SPLIT:
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ane_frac = 0.0
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elif ic > oc * 2:
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ane_frac = 0.0 # Wide→narrow: ANE inefficient (down_proj)
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elif oc < SPLIT_ALIGN * 2:
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ane_frac = 0.0
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else:
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ane_frac = 0.65
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self.ane_frac = ane_frac
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if ane_frac <= 0:
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self.mode = 'gpu'
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return
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self.mode = 'split'
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self.ane = bridge
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self.ane_oc = (int(oc * ane_frac) // SPLIT_ALIGN) * SPLIT_ALIGN
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self.gpu_oc = oc - self.ane_oc
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if self.ane_oc < SPLIT_ALIGN or self.gpu_oc < 1:
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self.mode = 'gpu'
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return
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self.h_ane = bridge.load(ic, self.ane_oc, seq, w_np[:self.ane_oc, :])
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self.buf_ane = np.empty((seq, self.ane_oc), dtype=np.float32) # ANE FP32 output
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self.buf_ane_f16 = np.empty((seq, self.ane_oc), dtype=np.float16) # FP16 cast buffer
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# GPU weight for split path
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self._is_quantized = isinstance(layer, nn.QuantizedLinear)
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if self._is_quantized:
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# Re-quantize GPU portion as QuantizedLinear → native quantized_matmul
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w_gpu_fp32 = mx.array(w_np[self.ane_oc:, :]) # [gpu_oc, ic] float32
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w_q, scales, biases = mx.quantize(w_gpu_fp32,
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group_size=layer.group_size,
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bits=layer.bits)
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self._gpu_layer = nn.QuantizedLinear(
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ic, self.gpu_oc, bias=False,
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group_size=layer.group_size, bits=layer.bits)
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self._gpu_layer.weight = w_q
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self._gpu_layer.scales = scales
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self._gpu_layer.biases = biases
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mx.eval(self._gpu_layer.parameters())
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self._w_gpu = None # not used for quantized path
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else:
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self._gpu_layer = None
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self._w_gpu = None
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if input_group is not None:
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self._grp = input_group
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else:
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self._grp = _InputGroup(ic, seq)
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self._is_first = True
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@classmethod
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def set_prefill(cls, enabled):
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cls._prefill_mode = enabled
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def __call__(self, x):
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# decode / gpu-only / short seq: use original nn.Linear
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if self.mode == 'gpu' or not SplitLinear._prefill_mode:
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return self._orig(x)
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L = x.shape[-2] if x.ndim == 3 else x.shape[0]
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if L < MIN_SEQ_FOR_SPLIT:
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return self._orig(x)
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# ── prefill split path (zero-copy + concurrent ANE/GPU) ──
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orig_shape = x.shape
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# Input preparation (shared or fresh) — row-major [L, IC] FP32
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if self._is_first:
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inp_np, x_2d, L = self._grp.prepare(x)
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else:
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inp_np, x_2d, L = self._grp.get()
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# ANE: launch in worker thread (row-major path, vDSP transpose in C)
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out_buf = self.buf_ane[:L] # [L, ane_oc] view
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fut = _ane_pool.submit(self.ane.run_rowmajor, self.h_ane, inp_np, L, out_buf)
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# GPU: matmul with GPU portion weight
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if self._gpu_layer is not None:
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# Quantized: use native quantized_matmul via QuantizedLinear
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gpu_out = self._gpu_layer(x_2d)
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elif self._w_gpu is not None:
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gpu_out = x_2d @ self._w_gpu.T
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else:
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w_gpu = self._orig.weight[self.ane_oc:, :]
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gpu_out = x_2d @ w_gpu.T
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mx.eval(gpu_out) # sync GPU — enables concurrent ANE execution
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# Wait for ANE
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fut.result()
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# Merge: numpy FP32→FP16 cast + lazy concat
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np.copyto(self.buf_ane_f16[:L], out_buf, casting='same_kind')
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ane_out = mx.array(self.buf_ane_f16[:L]) # [L, ane_oc] FP16
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merged = mx.concatenate([ane_out, gpu_out], axis=-1)
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if len(orig_shape) == 3:
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merged = merged.reshape(orig_shape[0], orig_shape[1], -1)
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return merged
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def __repr__(self):
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if self.mode == 'gpu':
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return f"SplitLinear({self.name}, gpu_only, {self.ic}→{self.oc})"
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return (f"SplitLinear({self.name}, {self.ane_oc}ane+{self.gpu_oc}gpu, "
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f"{self.ic}→{self.oc}, frac={self.ane_frac:.0%})")
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# ─── Tree Walk ───
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def _find_linears(module, prefix=""):
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"""Walk MLX model tree, yield (parent, key, full_name, linear)."""
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if not hasattr(module, 'children'):
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return
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for attr_name, child in module.children().items():
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full_name = f"{prefix}.{attr_name}" if prefix else attr_name
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if isinstance(child, (nn.Linear, nn.QuantizedLinear)):
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yield (module, attr_name, full_name, child)
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elif isinstance(child, nn.Module):
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yield from _find_linears(child, full_name)
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elif isinstance(child, list):
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for i, v in enumerate(child):
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fname = f"{full_name}.{i}"
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if isinstance(v, (nn.Linear, nn.QuantizedLinear)):
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yield (child, i, fname, v)
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elif hasattr(v, 'children'):
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yield from _find_linears(v, fname)
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elif isinstance(child, dict):
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for k, v in child.items():
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fname = f"{full_name}.{k}"
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if isinstance(v, (nn.Linear, nn.QuantizedLinear)):
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yield (module, k, fname, v)
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elif hasattr(v, 'children'):
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yield from _find_linears(v, fname)
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elif hasattr(child, 'children'):
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yield from _find_linears(child, full_name)
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def _get_input_dims(layer):
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"""Get true input dimensions for nn.Linear or nn.QuantizedLinear."""
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if isinstance(layer, nn.QuantizedLinear):
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return layer.weight.shape[-1] * 32 // layer.bits
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return layer.weight.shape[-1]
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def patch_model(model, seq, bridge=None, verbose=True):
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"""
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Patch all linear layers with SplitLinear.
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Same-input projections share an InputGroup:
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- Q/K/V share one (same hidden_state input)
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- Gate/Up share one (same hidden_state after attn)
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- O and Down each get their own (unique inputs)
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Returns: bridge instance.
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"""
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if bridge is None:
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bridge = ANEBridge.shared()
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lang = model.language_model
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lm = lang.model
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N = len(lm.layers)
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n_split = n_gpu = 0
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for li in range(N):
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la = lm.layers[li]
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attn = la.self_attn
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mlp = la.mlp
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ic_attn = _get_input_dims(attn.q_proj)
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ic_mlp = _get_input_dims(mlp.gate_proj)
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# Q/K/V share input group
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qkv_grp = _InputGroup(ic_attn, seq)
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for i, name in enumerate(('q_proj', 'k_proj', 'v_proj')):
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orig = getattr(attn, name)
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sl = SplitLinear(orig, bridge, seq,
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name=f"layer.{li}.{name}",
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input_group=qkv_grp,
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is_first=(i == 0))
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setattr(attn, name, sl)
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n_split += 1 if sl.mode == 'split' else 0
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n_gpu += 1 if sl.mode == 'gpu' else 0
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# O proj — own input
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sl = SplitLinear(attn.o_proj, bridge, seq,
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name=f"layer.{li}.o_proj")
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attn.o_proj = sl
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n_split += 1 if sl.mode == 'split' else 0
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n_gpu += 1 if sl.mode == 'gpu' else 0
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# Gate/Up share input group
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gu_grp = _InputGroup(ic_mlp, seq)
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for i, name in enumerate(('gate_proj', 'up_proj')):
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orig = getattr(mlp, name)
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sl = SplitLinear(orig, bridge, seq,
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name=f"layer.{li}.{name}",
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input_group=gu_grp,
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is_first=(i == 0))
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setattr(mlp, name, sl)
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n_split += 1 if sl.mode == 'split' else 0
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n_gpu += 1 if sl.mode == 'gpu' else 0
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# Down proj — own input (auto GPU-only due to IC>OC*2)
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sl = SplitLinear(mlp.down_proj, bridge, seq,
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name=f"layer.{li}.down_proj")
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mlp.down_proj = sl
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n_split += 1 if sl.mode == 'split' else 0
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n_gpu += 1 if sl.mode == 'gpu' else 0
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if verbose:
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print(f"[SplitLinear] {N} layers: {n_split} split, {n_gpu} gpu-only")
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print(f"[SplitLinear] ANE models: {bridge.model_count}")
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return bridge
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# ─── Self-test ───
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if __name__ == '__main__':
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import sys, time
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from mlx_vlm.utils import load as vlm_load
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from mlx_vlm.models.cache import KVCache
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from mlx.utils import tree_flatten
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SEQ = int(sys.argv[1]) if len(sys.argv) > 1 else 512
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N_W = 3; N_B = 10
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FP16_MODEL = '~/Downloads/weights/mlx/Qwen3-VL-2B-Instruct-16bit'
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print(f"\n{'='*60}")
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print(f" SplitLinear Self-Test (seq={SEQ})")
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print(f"{'='*60}\n")
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model, _ = vlm_load(FP16_MODEL)
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# Cast to true FP16
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flat = tree_flatten(model.trainable_parameters())
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fp16 = [(k, v.astype(mx.float16)) for k, v in flat]
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model.load_weights(fp16)
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mx.eval(model.parameters())
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lang = model.language_model
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N = lang.args.num_hidden_layers
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ids = mx.ones((1, SEQ), dtype=mx.int32)
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pos = mx.broadcast_to(mx.arange(SEQ).reshape(1, SEQ)[None, :, :], (3, 1, SEQ))
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mx.eval(ids, pos)
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# GPU baseline
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print("[1/3] GPU FP16 baseline")
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for _ in range(N_W):
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c = [KVCache() for _ in range(N)]
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mx.eval(lang(ids, cache=c, position_ids=pos).logits)
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ts = []
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for _ in range(N_B):
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c = [KVCache() for _ in range(N)]
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t0 = time.perf_counter()
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mx.eval(lang(ids, cache=c, position_ids=pos).logits)
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ts.append((time.perf_counter()-t0)*1000)
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bl = float(np.median(ts))
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print(f" {bl:.1f}ms\n")
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||||
|
||||
# Reference logits (FP32 for cos_sim)
|
||||
c_ref = [KVCache() for _ in range(N)]
|
||||
ref = np.array(lang(ids, cache=c_ref, position_ids=pos).logits.astype(mx.float32))
|
||||
|
||||
# Patch
|
||||
print("[2/3] Patch + benchmark")
|
||||
bridge = patch_model(model, SEQ)
|
||||
SplitLinear.set_prefill(True)
|
||||
|
||||
for _ in range(N_W):
|
||||
c = [KVCache() for _ in range(N)]
|
||||
mx.eval(lang(ids, cache=c, position_ids=pos).logits)
|
||||
|
||||
# Accuracy
|
||||
c_hyb = [KVCache() for _ in range(N)]
|
||||
hyb = np.array(lang(ids, cache=c_hyb, position_ids=pos).logits.astype(mx.float32))
|
||||
cos = float(np.dot(ref.flatten(), hyb.flatten()) /
|
||||
(np.linalg.norm(ref.flatten()) * np.linalg.norm(hyb.flatten()) + 1e-12))
|
||||
top1 = float((ref.argmax(-1) == hyb.argmax(-1)).mean() * 100)
|
||||
print(f" cos={cos:.6f}, top1={top1:.1f}%")
|
||||
|
||||
# Benchmark
|
||||
ts = []
|
||||
for i in range(N_B):
|
||||
c = [KVCache() for _ in range(N)]
|
||||
t0 = time.perf_counter()
|
||||
mx.eval(lang(ids, cache=c, position_ids=pos).logits)
|
||||
t = (time.perf_counter()-t0)*1000
|
||||
ts.append(t)
|
||||
print(f" Run {i+1}: {t:.1f}ms")
|
||||
med = float(np.median(ts))
|
||||
|
||||
print(f"\n{'='*60}")
|
||||
print(f" GPU FP16: {bl:.1f}ms")
|
||||
print(f" SplitLinear: {med:.1f}ms ({bl/med:.3f}x)")
|
||||
print(f" cos={cos:.6f} top1={top1:.1f}%")
|
||||
print(f" delta: {med - bl:+.1f}ms")
|
||||
print(f"{'='*60}")
|
||||
Reference in New Issue
Block a user