51 lines
2.2 KiB
Text
51 lines
2.2 KiB
Text
# ktune sysctl settings for EL 5 servers
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# 256 KB default performs well experimentally, and is often recommended by ISVs.
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net.core.rmem_default = 262144
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net.core.wmem_default = 262144
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# When opening a high-bandwidth connection while the receiving end is under
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# memory pressure, disk I/O may be necessary to free memory for the socket,
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# making disk latency the effective latency for the bandwidth-delay product
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# initially. For 10 Gb ethernet and SCSI, the BDP is about 5 MB. Allow 8 MB
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# to account for overhead, to ensure that new sockets can saturate the medium
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# quickly.
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net.core.rmem_max = 8388608
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net.core.wmem_max = 8388608
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# Allow a deep backlog for 10 Gb and bonded Gb ethernet connections
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net.core.netdev_max_backlog = 10000
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# Always have one page available, plus an extra for overhead, to ensure TCP NFS
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# pageout doesn't stall under memory pressure. Default to max unscaled window,
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# plus overhead for rmem, since most LAN sockets won't need to scale.
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net.ipv4.tcp_rmem = 8192 87380 8388608
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net.ipv4.tcp_wmem = 8192 65536 8388608
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# Always have enough memory available on a UDP socket for an 8k NFS request,
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# plus overhead, to prevent NFS stalling under memory pressure. 16k is still
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# low enough that memory fragmentation is unlikely to cause problems.
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net.ipv4.udp_rmem_min = 16384
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net.ipv4.udp_wmem_min = 16384
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# Ensure there's enough memory to actually allocate those massive buffers to a
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# socket.
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net.ipv4.tcp_mem = 8388608 12582912 16777216
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net.ipv4.udp_mem = 8388608 12582912 16777216
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# Filesystem I/O is usually much more efficient than swapping, so try to keep
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# swapping low. It's usually safe to go even lower than this on systems with
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# server-grade storage.
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vm.swappiness = 30
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# If a workload mostly uses anonymous memory and it hits this limit, the entire
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# working set is buffered for I/O, and any more write buffering would require
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# swapping, so it's time to throttle writes until I/O can catch up. Workloads
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# that mostly use file mappings may be able to use even higher values.
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vm.dirty_ratio = 50
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# Ensure there's always some easily-dropped pagecache if the system is under
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# memory pressure from cached files, since it's much faster to page back in than
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# swap.
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# Doesn't exist for 2.6.30++ anymore
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# vm.pagecache = 90
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