Addressing file system performance issues on NUMA machines
This document (7008919) is provided subject to the disclaimer at the end of this document.
A problem occurs if the machine is not tuned to fit within a NUMA partition. The server can stall as the system performs the work necessary to keep the process local to a node. These stalls can be significant if the process is also writing data. There are five recommendations as to how the problem may be mitigated.
1. Disable zone_reclaim if the workload has not been partitioned to fit within NUMA nodes with:
echo 0 >/proc/sys/vm/zone_reclaim_mode2. Disable NUMA support in the BIOS, effectively using the interleave memory policy for all processes.
3. Use numactl to use the interleave memory policy on the processes writing data by preceding the process start command with
numactl --interleave=all <command>
4. Tune vm.dirty_background_bytes to a value based on the backing storage such that stalls due to IO are within an acceptable margin:
echo $((128*1024*1024)) >/proc/sys/vm/dirty_background_bytes echo $((1024*1024*1024)) >/proc/sys/vm/dirty_bytesTo set one or several of these parameters permanently edit the file /etc/sysctl.conf
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- Document ID:7008919
- Creation Date: 30-Jun-2011
- Modified Date:03-Mar-2020
- SUSE Linux Enterprise Server
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