ggml-org/llama.cpp

Eval bug: wrong default threads in llama-bench

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#17,611 opened on Nov 30, 2025

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good first issuelow severityperformance

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Description

Name and Version

latest commit: https://github.com/ggml-org/llama.cpp/commit/fa0465954faef9d7170b967ad89f8bc5303a32f3

llama-bench using by default wrong threads.

Linux server with NUMA nodes

Operating systems

Linux

GGML backends

CPU

Hardware

Supermicro X10dri Dual CPU

Contributor guide

Research direction
Investigate the default thread count selection logic in llama bench, focusing on how it detects CPU topology and handles NUMA systems.
Tech stack
cpp
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Mostly clear
Prerequisites
C++threading concepts
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70