Fix high SoftIRQ on 4.13 kernel

Create /etc/sysctl.d/99-network-tuning.conf file

touch /etc/sysctl.d/99-network-tuning.conf

Insert the following text into /etc/sysctl.d/99-network-tuning.conf

The code below also contains various buffer updates.

# http://www.nateware.com/linux-network-tuning-for-2013.html
# Increase Linux autotuning TCP buffer limits
# Set max to 16MB for 1GE and 32M (33554432) or 54M (56623104) for 10GE
# Don't set tcp_mem itself! Let the kernel scale it based on RAM.
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.core.rmem_default = 16777216
net.core.wmem_default = 16777216
net.core.optmem_max = 40960 

# cloudflare uses this for balancing latency and throughput
# https://blog.cloudflare.com/the-story-of-one-latency-spike/
net.ipv4.tcp_rmem = 4096 1048576 2097152 

net.ipv4.tcp_wmem = 4096 65536 16777216

# Also increase the max packet backlog
net.core.netdev_max_backlog = 100000
net.core.netdev_budget = 50000

# Make room for more TIME_WAIT sockets due to more clients,
# and allow them to be reused if we run out of sockets
net.ipv4.tcp_max_syn_backlog = 30000
net.ipv4.tcp_max_tw_buckets = 2000000
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_fin_timeout = 10

# Disable TCP slow start on idle connections
net.ipv4.tcp_slow_start_after_idle = 0

# If your servers talk UDP, also up these limits
net.ipv4.udp_rmem_min = 8192
net.ipv4.udp_wmem_min = 8192

# Actual fix for high softirq in 4.13
net.core.netdev_budget_usecs = 5000

Reboot the server

/sbin/reboot

Revision #1
Created Mon, Jul 1, 2019 11:09 AM by Tamas Toth
Updated Mon, Jul 1, 2019 11:10 AM by Tamas Toth