ubuntu kernel tuning script

ubuntu-kernel-tuning.sh

#!/bin/bash
#vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4:
#
# Author : Nicolas Brousse <nicolas@brousse.info>
# From : https://www.shell-tips.com/2010/09/13/linux-sysctl-configuration-and-tuning-script/
#
# Added kernel version < 2.6.33 set net.ipv4.tcp_congestion_control=htcp
# Notes :
#   This script is a simple "helper" to configure your sysctl.conf on linux
#   There is no silver bullet. Don't expect the perfect setup, review comments
#   and adapt the parameters to your needs and application usage.
#
#   Use this script at your OWN risk. There is no guarantee whatsoever.
#
# License :
#   This work is licenced under the CC-GNU LGPL version 2.1 or later.
#   To view a copy of this licence, visit http://creativecommons.org/licenses/LGPL/2.1/
#   or send a letter to :
#
#           Creative Commons
#           171 Second Street, Suite 300
#           San Francisco, California 94105, USA
#
# May 2012, Jon Zobrist <jon@jonzobrist.com> http://www.jonzobrist.com/
# Things added : 
# Apache max file handlers update to /etc/security/limits.conf
# Check and add pam_limits.so is loaded by the su program (as many things run via su)
# Backing up of previous sysctl.conf file
# Merging of previous sysctl.conf settings if new settings don't override
# tcp_available_congestion_control detection and setting
# Updates hosted on github at https://github.com/jonzobrist/Bash-Admin-Scripts

host=$(hostname)

ARCH=$(uname -m)
KERNEL_STRING=$(uname -r | sed -e 's/[^0-9]/ /g')
KERNEL_VERSION=$(echo "${KERNEL_STRING}" | awk '{ print $1 }')
MAJOR_VERSION=$(echo "${KERNEL_STRING}" | awk '{ print $2 }')
MINOR_VERSION=$(echo "${KERNEL_STRING}" | awk '{ print $3 }')
echo "${KERNEL_VERSION}.${MAJOR_VERSION}.${MINOR_VERSION}"
CURRENT_SYSCTL_FILE=/tmp/sysctl-existing-$(date +%F-%s)

touch ${CURRENT_SYSCTL_FILE}
#chmod og-rwx ${CURRENT_SYSCTL_FILE}
grep -v '^#' /etc/sysctl-1.conf | grep . >> ${CURRENT_SYSCTL_FILE}
BACKUP_SYSCTL="sysctl.conf-$(date +%F-%s)"
echo "moving sysctl.conf to /etc/${BACKUP_SYSCTL}"
mv /etc/sysctl.conf /etc/${BACKUP_SYSCTL}

which bc
if [ $? -ne 0 ]; then
    echo "This script require GNU bc, cf. http://www.gnu.org/software/bc/"
    echo "On Linux Debian/Ubuntu you can install it by doing : apt-get install bc"
fi

echo "Update sysctl for $host"

mem_bytes=$(awk '/MemTotal:/ { printf "%0.f",$2 * 1024}' /proc/meminfo)
shmmax=$(echo "$mem_bytes * 0.90" | bc | cut -f 1 -d '.') 
shmall=$(expr $mem_bytes / $(getconf PAGE_SIZE))
max_orphan=$(echo "$mem_bytes * 0.10 / 65536" | bc | cut -f 1 -d '.')
file_max=$(echo "$mem_bytes / 4194304 * 256" | bc | cut -f 1 -d '.')
max_tw=$(($file_max*2))
min_free=$(echo "($mem_bytes / 1024) * 0.01" | bc | cut -f 1 -d '.')

if [ "${KERNEL_VERSION}" -lt 3 ] && [ "${MAJOR_VERSION}" -lt 7 ] && [ "${MINOR_VERSION}" -lt 33 ]
 then
	CONGESTION_CONTROL="htcp"
 else
	if [ "$(sysctl net.ipv4.tcp_available_congestion_control | grep reno)" ]
	 then
		CONGESTION_CONTROL="reno"
	else
		CONGESTION_CONTROL="cubic"
	fi
fi

if [ "$1" != "ssd" ]; then
    vm_dirty_bg_ratio=5
    vm_dirty_ratio=15
else
    # This setup is generally ok for ssd and highmem servers
    vm_dirty_bg_ratio=3
    vm_dirty_ratio=5
fi
 
>/etc/sysctl.conf cat << EOF 
# Disable syncookies (syncookies are not RFC compliant and can use too muche resources)
net.ipv4.tcp_syncookies = 0
# Basic TCP tuning
net.ipv4.tcp_keepalive_time = 600
net.ipv4.tcp_synack_retries = 3
net.ipv4.tcp_syn_retries = 3
# RFC1337
net.ipv4.tcp_rfc1337 = 1
# Defines the local port range that is used by TCP and UDP
# to choose the local port
net.ipv4.ip_local_port_range = 1024 65535
# Log packets with impossible addresses to kernel log
net.ipv4.conf.all.log_martians = 1
# Minimum interval between garbage collection passes This interval is
# in effect under high memory pressure on the pool
net.ipv4.inet_peer_gc_mintime = 5
# Disable Explicit Congestion Notification in TCP
net.ipv4.tcp_ecn = 0
# Enable window scaling as defined in RFC1323
net.ipv4.tcp_window_scaling = 1
# Enable timestamps (RFC1323)
net.ipv4.tcp_timestamps = 1
# DISable select acknowledgments
net.ipv4.tcp_sack = 0
# Enable FACK congestion avoidance and fast restransmission
net.ipv4.tcp_fack = 1
# DISABLE Allows TCP to send "duplicate" SACKs
net.ipv4.tcp_dsack = 0
# Controls IP packet forwarding
net.ipv4.ip_forward = 0
# No controls source route verification (RFC1812)
net.ipv4.conf.default.rp_filter = 0
# Enable fast recycling TIME-WAIT sockets
net.ipv4.tcp_tw_recycle = 1
# TODO : change TCP_SYNQ_HSIZE in include/net/tcp.h
# to keep TCP_SYNQ_HSIZE*16<=tcp_max_syn_backlog
net.ipv4.tcp_max_syn_backlog = 20000
# tells the kernel how many TCP sockets that are not attached
# to any user file handle to maintain
net.ipv4.tcp_max_orphans = $max_orphan
# How may times to retry before killing TCP connection, closed by our side
net.ipv4.tcp_orphan_retries = 1
# how long to keep sockets in the state FIN-WAIT-2
# if we were the one closing the socket
net.ipv4.tcp_fin_timeout = 20
# maximum number of sockets in TIME-WAIT to be held simultaneously
net.ipv4.tcp_max_tw_buckets = $max_tw
# don't cache ssthresh from previous connection
net.ipv4.tcp_no_metrics_save = 1
net.ipv4.tcp_moderate_rcvbuf = 1
# increase Linux autotuning TCP buffer limits
net.ipv4.tcp_rmem = 4096 87380 16777216 
net.ipv4.tcp_wmem = 4096 65536 16777216
# increase TCP max buffer size
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.core.netdev_max_backlog = 2500
net.core.somaxconn = 65000
vm.swappiness = 0
# You can monitor the kernel behavior with regard to the dirty
# pages by using grep -A 1 dirty /proc/vmstat
vm.dirty_background_ratio = $vm_dirty_bg_ratio
vm.dirty_ratio = $vm_dirty_ratio
# required free memory (set to 1% of physical ram)
vm.min_free_kbytes = $min_free
# system open file limit
fs.file-max = $file_max
# Core dump suidsafe
fs.suid_dumpable = 2 
kernel.printk = 4 4 1 7
kernel.core_uses_pid = 1
kernel.sysrq = 0
kernel.msgmax = 65536
kernel.msgmnb = 65536
# Maximum shared segment size in bytes
kernel.shmmax = $shmmax
# Maximum number of shared memory segments in pages
kernel.shmall = $shmall
net.ipv4.tcp_congestion_control=${CONGESTION_CONTROL}
EOF

LIMITS_SET=$(grep 'www-data' /etc/security/limits.conf | grep nofile | grep -v '^#')
if [ "${LIMITS_SET}" ]
 then
	echo "www-data limits for nofiles already set to"
	grep 'www-data' /etc/security/limits.conf | grep nofil | grep -v '^#'
 else
	echo "Setting limits for user www-data in /etc/security/limits.conf"
	echo "www-data soft nofile 50000" >> /etc/security/limits.conf
	echo "www-data hard nofile 60000" >> /etc/security/limits.conf
fi

PAM_SU=$(grep pam_limits.so /etc/pam.d/su | grep -v '^#')
if [ "${PAM_SU}" ]
 then
	echo "pam_limits is already set in /etc/pam.d/su"
 else
	echo "Adding pam limits to /etc/pam.d/su"
	echo "session    required   pam_limits.so" >> /etc/pam.d/su
fi

SAVEIFS=$IFS
IFS=$(echo -en "\n\b")
for LINE in $(grep -v '^#' ${CURRENT_SYSCTL_FILE} | grep . )
 do
	unset RESULT
	MY_VAR=$(echo ${LINE} | awk '{ print $1 }')
	RESULT=$(grep ${MY_VAR} /etc/sysctl.conf)
	if [ "${RESULT}" ]
	 then
		echo "${MY_VAR} exists in new sysctl.conf, skipping"
	 else
		echo "Adding ${MY_VAR} from old sysctl.conf to new"
		echo "${LINE}"
		echo "${LINE}" >> /etc/sysctl.conf
	fi
	
done
IFS=$SAVEIFS

/sbin/sysctl -p /etc/sysctl.conf
exit $?