arXiv:2608.28968cs.AIcs.LG2026-08

针对语义搜索的召回瓶颈,提出对齐策略的高效检索框架。

Efficient GPU Retrieval for Semantic Search

  • 将嵌入按类别分段,按最小/中位数规则聚合评分
  • 在21000个查询上提升离线相关性,覆盖多种筛选组合
  • 两阶段GPU架构支持每副本500 QPS以上,精度接近全精度

LinkedIn的语义搜索需在数亿条个人资料中响应自然语言查询,如“柏林的金融科技创始人且曾在支付领域工作”。当前部署的相关性策略为瓶颈导向:每个非协商性筛选维度必须满足,通过预设的LLM分级相关性(GR)判断器以固定最小值/中位数聚合各维度评分。而余弦相似度平均证据,使单一维度强匹配可能掩盖其他维度失败,限制第一阶段(L0)检索器的召回率。本文提出对齐策略的检索框架:嵌入被划分为八个类别监督段,服务时分数遵循相同最小/中位数规则;多向量检索中,每标签文档槽独立计算段得分并取最大值。轻量级单槽第一阶段评分器生成高召回候选,尺度不变的相对范数门控确保训练、评估与服务中类别激活一致。在21,000个保留查询上,该表示相比匹配容量基线提升离线相关性,增益广泛分布于各类筛选组合。通过两阶段GPU架构实现服务:FP8粗排器对全库评分,每分片容量提升71%,第一阶段矩阵乘法吞吐量提高36%;随后FP16阶段精确重排超采样候选集,恢复99.6%-99.8%的全FP16召回率,每分片副本达到500+ QPS。成员随机化A/B测试显示,在不变的GR判别器下,探索性查询Precision@10从63.7%升至79.0%,导航类查询Precision@1从65.5%升至74.7%,盲评独立确认Precision@10提升。

原文摘要 · Abstract (English)

Semantic Search on LinkedIn must retrieve relevant profiles from a corpus of hundreds of millions in response to natural-language queries such as "a fintech founder in Berlin who worked in payments." The deployed relevance policy is bottleneck-oriented: every active non-negotiable facet must be satisfied, and a pre-existing LLM Graded Relevance (GR) judge operationalizes this through a fixed min/median aggregation over facet grades. Cosine similarity instead averages evidence, letting a strong match on one facet mask failure on another, capping the recall of the first-stage (L0) retriever. We present a policy-aligned retrieval framework: embeddings are partitioned into eight category-supervised segments whose scores follow the same min/median rule at serving time; for multi-vector retrieval, this segment score is computed independently per tagged document slot and maximized across slots. A lightweight single-slot Stage-1 scorer generates high-recall candidates, while scale-invariant relative-norm gating keeps category activation consistent across training, evaluation, and serving. On 21K held-out queries, this representation improves offline relevance over a matched-capacity baseline, with gains broadly distributed across facet combinations. We serve this framework with a two-stage GPU architecture: an FP8 coarse ranker scores the full corpus, increasing per-shard capacity by 71% and Stage-1 matmul throughput by 36%, then an FP16 stage exactly re-ranks an oversampled candidate set, recovering 99.6-99.8% of full-FP16 recall at over 500 QPS per shard replica. In a member-randomized A/B test, exploratory-query Precision@10 under the unchanged GR judge rises from 63.7% to 79.0% and navigational Precision@1 from 65.5% to 74.7%, with a blinded human evaluation independently confirming the Precision@10 gain.

语义搜索检索优化GPU加速多向量

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