24-28 August 2020
US/Pacific timezone

NUMA topology limitations

25 Aug 2020, 08:30
30m
Microconference1/Virtual-Room (LPC 2020)

Microconference1/Virtual-Room

LPC 2020

150
Scheduler MC Scheduler MC

Speaker

Valentin Schneider (Arm Ltd)

Description

Recent experiments 1 on more "creative" hardware have shown that the NUMA topology code has some unwritten assumptions which can be broken relatively easily. While the pictured topology may be considered questionable, somewhat saner topologies can trigger the same class of issues, which can be tested via e.g. QEMU.

The idea would be to point out said limitations, discuss if / how much we really care and potential ways forward.

Note: I plan to have an RFC on the list highlighting the issues in the above link, along with simplified QEMU reproducers, in a few weeks' time.

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Primary author

Presentation Materials