mukesh
91b63eb9f6
Adds compute_parallelism_sensitivity() + ParallelismSensitivityRow to auto_explore.py. For a baseline ConfigScore (picked from the Pareto set), sweeps each parallelism knob (CP, TP, PP, DP, EP) individually while holding others fixed. Reports latency + memory-fit per value. Sweep values start at 1 and step by 2 (multiples of 2 rather than only powers of 2), giving finer granularity for the visual than the enumerator's sparser set. CP goes up to 256 (per real-deployment scale), TP to 64, PP to 32. New UI panel in Auto Explore tab: 5 subplots (log/log), one per knob: - Solid line = latency where the config fits memory - Red X markers = infeasible (out of budget) - Dotted vertical line = baseline value User picks which Pareto row is the "baseline" via a number input; the sensitivity chart re-computes around it. Behaviour caveat noted during verification: for large PP the FFN AR can cross a SIP boundary (uses stage_latencies.py:730 sips_used tier selection), producing a step-up in latency. This is the existing model's choice, honestly reflected in the chart. Whether the FFN AR should span only one PP stage's ranks (thus not cross SIPs) is a separate discussion about stage_latencies.py. Verified: - 11 pytest tests pass (added 2 new for parallelism sensitivity) - Smoke: at Llama 70B decode 128K with baseline CP=8/TP=16/PP=1/DP=1: * CP sweep: 4 fits, 8 = baseline optimum, 16+ overshoots memory * TP sweep: 8/16 fit, 16 = baseline optimum, 32 slower (spans SIPs) * PP sweep: 1 = baseline, 2+ slower due to sips_used tier drop for FFN AR * DP sweep: same shape as PP * EP sweep: monotone decreasing (bigger EP = smaller per-PE FFN) Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
418 lines
16 KiB
Python
418 lines
16 KiB
Python
"""Auto-explore parallelism configuration space and rank by Pareto frontier.
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Extends the existing ``autosuggest`` (memory-only, single winner) to the
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full 9-knob search (CP, TP, PP, DP, kv_shard_mode, ffn_shard_scope,
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tp_placement, cp_placement, cp_ring_variant) with four objectives:
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- min total_latency_ns (single-request decode/prefill step)
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- max throughput_tok_s (naive tokens/sec = 1 / latency for single-req)
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- max efficiency_score (geo-mean of compute + BW utilization)
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- min pes_used
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Reuses ``stage_latencies`` and ``memory_layout`` as the physics; adds
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enumeration + 4D Pareto sort on top.
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Analytical model runs in ~microseconds per config, so the full sweep
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(~5-10k feasible configs after pruning) completes in a few seconds.
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"""
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from __future__ import annotations
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import math
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from collections.abc import Iterator
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from dataclasses import dataclass, field, replace
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from .memory_layout import compute_memory
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from .model_config import FullConfig, MachineParams, ModelConfig, TopologyConfig
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from .stage_latencies import all_ffn_stages, all_stages
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# ── Parallelism sensitivity sweep values (see compute_parallelism_sensitivity)
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# Multiples of 2 (finer grid than powers of 2 alone), capped at values that
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# are physically meaningful for the modelled topology.
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_PARALLELISM_SWEEP_VALUES = {
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"cp": (1, 2, 4, 6, 8, 10, 12, 14, 16, 24, 32, 48, 64, 96, 128, 192, 256),
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"tp": (1, 2, 4, 6, 8, 10, 12, 14, 16, 24, 32, 48, 64),
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"pp": (1, 2, 4, 6, 8, 10, 12, 14, 16, 20, 24, 32),
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"dp": (1, 2, 4, 6, 8, 12, 16),
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"ep": (1, 2, 4, 6, 8, 12, 16, 32),
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}
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# ── Search space ─────────────────────────────────────────────────────
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_CP_OPTIONS = (1, 2, 4, 8, 16, 32, 64, 96)
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_TP_OPTIONS = (1, 2, 4, 8, 16, 32)
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_PP_OPTIONS = (1, 2, 4, 8, 16)
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_DP_OPTIONS = (1, 2, 4)
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_KV_SHARD_MODES = ("split", "replicate")
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_FFN_SHARD_SCOPES = ("TP", "TP+CP", "TP+CP+DP")
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_TP_PLACEMENTS = ("pe", "cube")
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_CP_PLACEMENTS = ("cube", "pe")
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_CP_RING_VARIANTS = ("kv", "qoml")
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# ── Result types ─────────────────────────────────────────────────────
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@dataclass
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class ConfigScore:
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"""A single (config, computed-metrics) tuple. All floats in SI units
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(seconds, tokens/sec, dimensionless) unless suffixed otherwise."""
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# ── Config (the 9 knobs) ─────
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cp: int
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tp: int
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pp: int
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dp: int
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kv_shard_mode: str
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ffn_shard_scope: str
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tp_placement: str
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cp_placement: str
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cp_ring_variant: str
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# ── Objectives ─────
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total_latency_ns: float # ↓ minimize
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throughput_tok_s: float # ↑ maximize
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efficiency_score: float # ↑ maximize (0..1)
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pes_used: int # ↓ minimize
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# ── Info-only (not ranked on) ─────
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hbm_utilization: float # bytes_used / budget (0..1+; may exceed 1 if over-budget)
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weights_gb: float
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kv_gb: float
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transient_gb: float
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sips_used: int
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fits_memory: bool
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placement_valid: bool
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reason: str = ""
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@property
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def latency_us(self) -> float:
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return self.total_latency_ns / 1e3
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@property
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def latency_ms(self) -> float:
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return self.total_latency_ns / 1e6
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def as_topology(self, s_kv: int, mode: str) -> TopologyConfig:
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"""Reconstruct the TopologyConfig this score was computed for."""
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return TopologyConfig(
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cp=self.cp, tp=self.tp, pp=self.pp, dp=self.dp,
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s_kv=s_kv, mode=mode,
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kv_shard_mode=self.kv_shard_mode,
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ffn_shard_scope=self.ffn_shard_scope,
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tp_placement=self.tp_placement,
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cp_placement=self.cp_placement,
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cp_ring_variant=self.cp_ring_variant,
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)
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@dataclass
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class AutoExploreResult:
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model_name: str
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s_kv: int
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mode: str
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total_enumerated: int # after basic domain pruning
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total_feasible: int # after memory + placement checks
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all_scores: list[ConfigScore] = field(default_factory=list) # every feasible config
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pareto_scores: list[ConfigScore] = field(default_factory=list) # non-dominated set
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# ── Enumeration + pruning ────────────────────────────────────────────
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def enumerate_configs(
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model: ModelConfig,
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s_kv: int,
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mode: str,
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) -> Iterator[TopologyConfig]:
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"""Yield every domain-valid TopologyConfig.
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Domain rules (fast pruning; no memory check yet):
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- PP ≤ model.layers (can't have more stages than layers)
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- TP ≤ 4 × model.h_q (unrealistic head-dim splits above this)
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- Skip ffn_shard_scope containing 'DP' when DP=1 (redundant with plain 'TP+CP')
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- Skip cp_ring_variant='qoml' when CP=1 (no ring, variant is a no-op)
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"""
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for cp in _CP_OPTIONS:
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for tp in _TP_OPTIONS:
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if tp > 4 * model.h_q:
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continue
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for pp in _PP_OPTIONS:
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if pp > model.layers:
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continue
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for dp in _DP_OPTIONS:
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for kv_mode in _KV_SHARD_MODES:
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for ffn_scope in _FFN_SHARD_SCOPES:
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if "DP" in ffn_scope and dp == 1:
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continue
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for tp_place in _TP_PLACEMENTS:
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for cp_place in _CP_PLACEMENTS:
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for cp_ring in _CP_RING_VARIANTS:
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if cp == 1 and cp_ring == "qoml":
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continue
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yield TopologyConfig(
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cp=cp, tp=tp, pp=pp, dp=dp,
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s_kv=s_kv, mode=mode,
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kv_shard_mode=kv_mode,
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ffn_shard_scope=ffn_scope,
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tp_placement=tp_place,
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cp_placement=cp_place,
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cp_ring_variant=cp_ring,
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)
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# ── Scoring ──────────────────────────────────────────────────────────
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def _sum_visible_latency(cfg: FullConfig) -> float:
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"""Total single-request latency (seconds) across all model layers.
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A single request traverses every layer sequentially, whether the layers
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sit on one PP stage or are spread across many:
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- PP=1 : one rank holds all L layers, latency = L × per_layer
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- PP=K : K ranks each hold L/K layers, but request crosses all K
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stages sequentially → still L × per_layer
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PP therefore does NOT reduce single-request latency; it only improves
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throughput under batching. This function is the single-request cost, so
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we multiply by full model.layers regardless of PP.
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"""
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attn = sum(s.visible_s for s in all_stages(cfg))
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ffn = sum(s.visible_s for s in all_ffn_stages(cfg))
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per_layer = attn + ffn
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return per_layer * cfg.model.layers
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def _efficiency(cfg: FullConfig, latency_s: float) -> float:
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"""Geo-mean of compute-util and BW-util. Range ~ (0, 1].
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- compute_util = achieved_flops / (peak_flops × pes × latency)
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- bw_util = achieved_bytes / (peak_bw × pes × latency)
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"""
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if latency_s <= 0:
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return 0.0
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attn = all_stages(cfg)
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ffn = all_ffn_stages(cfg)
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layers = math.ceil(cfg.model.layers / cfg.topo.pp)
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total_flops = layers * sum(s.flops for s in attn + ffn)
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total_bytes = layers * sum(s.mem_bytes for s in attn + ffn)
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pes = cfg.topo.total_pes
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peak_flops = cfg.machine.peak_flops * pes
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peak_bw = cfg.machine.bw_hbm * pes
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compute_util = total_flops / (peak_flops * latency_s) if peak_flops > 0 else 0.0
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bw_util = total_bytes / (peak_bw * latency_s) if peak_bw > 0 else 0.0
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compute_util = min(1.0, max(0.0, compute_util))
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bw_util = min(1.0, max(0.0, bw_util))
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# Geo-mean; if either is 0 the score is 0 (avoids overrewarding lopsided configs).
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return math.sqrt(compute_util * bw_util)
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def score_config(cfg: FullConfig) -> ConfigScore:
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"""Compute all 4 objectives + info fields for one config.
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Feasibility (memory + placement) is stored but does NOT gate scoring —
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infeasible configs get returned with fits_memory=False so callers can
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filter or display them.
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"""
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mem = compute_memory(cfg)
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placement_ok = cfg.topo.placement_valid
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latency_s = _sum_visible_latency(cfg)
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throughput = 1.0 / latency_s if latency_s > 0 else 0.0
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efficiency = _efficiency(cfg, latency_s) if latency_s > 0 else 0.0
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fits = not mem.over_budget
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reason = ""
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if not fits:
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reason = (f"weights+KV+transient ({mem.used_bytes/1e9:.2f} GB) "
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f"exceeds per-PE budget ({mem.budget_bytes/1e9:.2f} GB)")
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elif not placement_ok:
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reason = (f"intra-cube demand ({cfg.topo.intra_cube_dims}) "
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f"exceeds PEs/cube ({cfg.topo.pes_per_cube_hw})")
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return ConfigScore(
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cp=cfg.topo.cp, tp=cfg.topo.tp, pp=cfg.topo.pp, dp=cfg.topo.dp,
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kv_shard_mode=cfg.topo.kv_shard_mode,
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ffn_shard_scope=cfg.topo.ffn_shard_scope,
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tp_placement=cfg.topo.tp_placement,
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cp_placement=cfg.topo.cp_placement,
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cp_ring_variant=cfg.topo.cp_ring_variant,
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total_latency_ns=latency_s * 1e9,
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throughput_tok_s=throughput,
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efficiency_score=efficiency,
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pes_used=cfg.topo.total_pes,
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hbm_utilization=mem.used_bytes / mem.budget_bytes if mem.budget_bytes > 0 else 0.0,
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weights_gb=mem.weights_bytes / 1e9,
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kv_gb=mem.kv_cache_bytes / 1e9,
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transient_gb=mem.transient_bytes / 1e9,
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sips_used=cfg.topo.sips_used,
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fits_memory=fits,
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placement_valid=placement_ok,
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reason=reason,
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)
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# ── Pareto sort ──────────────────────────────────────────────────────
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def _dominates(a: ConfigScore, b: ConfigScore) -> bool:
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"""True iff a is no worse than b on every axis AND strictly better on ≥ 1.
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Axes (with direction) — 3D Pareto:
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total_latency_ns ↓ (a ≤ b)
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pes_used ↓ (a ≤ b) — proxy for cost / deployment size
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efficiency_score ↑ (a ≥ b) — geo-mean of compute+BW utilization
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Note: ``throughput_tok_s`` is deliberately NOT a Pareto axis. For a
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single-request analysis, throughput = 1 / latency, so it's collinear
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with latency and would collapse the frontier. It stays on ConfigScore
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for display but doesn't participate in domination.
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"""
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no_worse = (
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a.total_latency_ns <= b.total_latency_ns
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and a.pes_used <= b.pes_used
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and a.efficiency_score >= b.efficiency_score
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)
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if not no_worse:
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return False
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strictly_better = (
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a.total_latency_ns < b.total_latency_ns
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or a.pes_used < b.pes_used
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or a.efficiency_score > b.efficiency_score
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)
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return strictly_better
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def pareto_frontier(scores: list[ConfigScore]) -> list[ConfigScore]:
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"""Extract non-dominated set on (latency↓, pe↓, throughput↑, efficiency↑).
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Only feasible configs (fits_memory AND placement_valid) participate; the
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non-feasible are excluded from the frontier (they can still be returned in
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``all_scores`` for informational display).
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O(N²) — fine for N up to ~50k with early exits.
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"""
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feasible = [s for s in scores if s.fits_memory and s.placement_valid]
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frontier: list[ConfigScore] = []
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for i, a in enumerate(feasible):
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dominated = False
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for j, b in enumerate(feasible):
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if i == j:
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continue
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if _dominates(b, a):
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dominated = True
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break
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if not dominated:
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frontier.append(a)
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return frontier
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# ── Parallelism sensitivity ─────────────────────────────────────────
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@dataclass
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class ParallelismSensitivityRow:
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"""One knob's sweep result: latency + fit at every tested value.
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All *other* parallelism knobs (including HW) are held at their baseline
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values, so this isolates the effect of just this one knob.
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"""
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knob: str # "cp" / "tp" / "pp" / "dp" / "ep"
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values: list[int] # tested values (from _PARALLELISM_SWEEP_VALUES)
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latencies_ns: list[float] # one per value; NaN when infeasible
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fits_flags: list[bool] # per-value memory+placement feasibility
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baseline_value: int # what the baseline config uses for this knob
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baseline_latency_ns: float
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def compute_parallelism_sensitivity(
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baseline: ConfigScore,
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model: ModelConfig,
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machine: MachineParams,
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s_kv: int,
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mode: str,
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) -> list[ParallelismSensitivityRow]:
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"""For each parallelism knob (CP, TP, PP, DP, EP), sweep its values
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holding the OTHER knobs fixed at the baseline. Reports latency + memory
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fit per value.
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Answers: 'if I only change this one knob, how does latency and memory
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fit change?' — the complement to auto_hardware.compute_sensitivity
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which does the same for hardware knobs.
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"""
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baseline_topo = baseline.as_topology(s_kv, mode)
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rows: list[ParallelismSensitivityRow] = []
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for knob, values in _PARALLELISM_SWEEP_VALUES.items():
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baseline_val = getattr(baseline_topo, knob, 1)
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# EP isn't stored on ConfigScore's as_topology output today (dp
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# attribute exists but ep does not always). Fall back to 1.
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latencies: list[float] = []
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fits: list[bool] = []
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for v in values:
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# Skip nonsensical values that would violate hard bounds.
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if knob == "pp" and v > model.layers:
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latencies.append(float("nan"))
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fits.append(False)
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continue
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if knob == "tp" and v > 4 * model.h_q:
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latencies.append(float("nan"))
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fits.append(False)
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continue
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# Build a variant TopologyConfig with just this one knob changed.
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trial = replace(baseline_topo, **{knob: v})
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cfg = FullConfig(model=model, topo=trial, machine=machine)
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score = score_config(cfg)
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latencies.append(score.total_latency_ns)
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fits.append(score.fits_memory and score.placement_valid)
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rows.append(ParallelismSensitivityRow(
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knob=knob,
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values=list(values),
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latencies_ns=latencies,
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fits_flags=fits,
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baseline_value=int(baseline_val),
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baseline_latency_ns=baseline.total_latency_ns,
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))
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return rows
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# ── Top-level driver ─────────────────────────────────────────────────
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def run_auto_explore(
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model: ModelConfig,
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machine: MachineParams,
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s_kv: int,
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mode: str = "decode",
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) -> AutoExploreResult:
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"""Enumerate all configs, score each, extract Pareto frontier.
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Returns both the full ``all_scores`` list (for the table view) and the
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``pareto_scores`` subset (for the scatter/highlight view). Both are sorted
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by total_latency_ns ascending.
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"""
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all_scores: list[ConfigScore] = []
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total_enumerated = 0
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for topo in enumerate_configs(model, s_kv, mode):
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total_enumerated += 1
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cfg = FullConfig(model=model, topo=topo, machine=machine)
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all_scores.append(score_config(cfg))
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all_scores.sort(key=lambda s: s.total_latency_ns)
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pareto = pareto_frontier(all_scores)
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pareto.sort(key=lambda s: s.total_latency_ns)
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feasible_count = sum(1 for s in all_scores if s.fits_memory and s.placement_valid)
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return AutoExploreResult(
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model_name=model.name,
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s_kv=s_kv,
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mode=mode,
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total_enumerated=total_enumerated,
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total_feasible=feasible_count,
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all_scores=all_scores,
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pareto_scores=pareto,
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)
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