PICO: Performance Insights for Collective Operations

Fuente: arXiv
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Auteurs principaux: Pasqualoni, Saverio, Bonato, Tommaso, Piarulli, Lorenzo, Hoefler, Torsten, Canini, Marco, De Sensi, Daniele
Format: Preprint
Publié: 2025
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author Pasqualoni, Saverio
Bonato, Tommaso
Piarulli, Lorenzo
Hoefler, Torsten
Canini, Marco
De Sensi, Daniele
author_facet Pasqualoni, Saverio
Bonato, Tommaso
Piarulli, Lorenzo
Hoefler, Torsten
Canini, Marco
De Sensi, Daniele
contents Collective operations are cornerstones of both HPC applications and large-scale AI training and inference, yet benchmarking them in a systematic and reproducible way remains difficult on modern systems due to the complexity of their hardware and software stacks. Existing suites primarily report end-to-end timings and offer limited support for controlled algorithm and configuration selection, fine-grained profiling, and capturing the runtime environment. We present PICO (Performance Insights for Collective Operations), an open-source framework that decouples portable experiment setup from platform execution, provides a backend-adaptive parameter selection interface across MPI and NCCL, supplies plain-MPI reference collective implementations, optionally instrumentable, and records the system configuration for reproducible comparisons. Evaluated on three major supercomputers, PICO shows that default collective algorithms and transport settings can be up to $5\times$ slower than the best available choice. It provides diagnostic evidence by isolating topology sensitive algorithmic choices and, through instrumentation, reveals detailed algorithmic breakdowns. To assess end-to-end effects of benchmark-informed tuning and evaluate application-level impacts, we replay open-source LLM training traces in ATLAHS simulator with optimized collective profiles identified by PICO, achieving reductions in training times of up to $44\%$.
format Preprint
id arxiv_https___arxiv_org_abs_2508_16809
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle PICO: Performance Insights for Collective Operations
Pasqualoni, Saverio
Bonato, Tommaso
Piarulli, Lorenzo
Hoefler, Torsten
Canini, Marco
De Sensi, Daniele
Distributed, Parallel, and Cluster Computing
Performance
Collective operations are cornerstones of both HPC applications and large-scale AI training and inference, yet benchmarking them in a systematic and reproducible way remains difficult on modern systems due to the complexity of their hardware and software stacks. Existing suites primarily report end-to-end timings and offer limited support for controlled algorithm and configuration selection, fine-grained profiling, and capturing the runtime environment. We present PICO (Performance Insights for Collective Operations), an open-source framework that decouples portable experiment setup from platform execution, provides a backend-adaptive parameter selection interface across MPI and NCCL, supplies plain-MPI reference collective implementations, optionally instrumentable, and records the system configuration for reproducible comparisons. Evaluated on three major supercomputers, PICO shows that default collective algorithms and transport settings can be up to $5\times$ slower than the best available choice. It provides diagnostic evidence by isolating topology sensitive algorithmic choices and, through instrumentation, reveals detailed algorithmic breakdowns. To assess end-to-end effects of benchmark-informed tuning and evaluate application-level impacts, we replay open-source LLM training traces in ATLAHS simulator with optimized collective profiles identified by PICO, achieving reductions in training times of up to $44\%$.
title PICO: Performance Insights for Collective Operations
topic Distributed, Parallel, and Cluster Computing
Performance
url https://arxiv.org/abs/2508.16809