Default pagecache reclaim policy on RHEL 5 NUMA systems can cause HPC performance degradation

Solution Verified - Updated -


High Performance Computing (HPC) applications running on Non-Uniform Memory Access (NUMA) hardware with Red Hat Enterprise Linux 5 (RHEL 5) can incur severe performance degradation when application memory allocation is forced off-node due to the local-node memory being full of clean unmapped pagecache pages. Applications with a large memory footprint may run an order of magnitude slower due to the increased non-local memory access latency and/or reduction in bandwidth across the NUMA fabric.


  • Red Hat Enterprise Linux 5 (GA or later)
  • NUMA capable hardware
  • A latency and/or bandwith sensitive application, e.g. the STREAMS benchmark.

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