linux performance tuning inode limit file descriptors tco, kernel etc

Inode limit:

Tune Linux for Performance

etc/sysctl.conf

File descriptors/ max of open files

/etc/sysctl.conf

# Increase size of file handles and inode cache
fs.file-max = 2097152

what is ulimit and how to change it permanently?

Setting       Soft/Hard
NoFiles       32768/65536
Filesize      unlimited/unlimited
Data          unlimited/unlimited
Stack         unlimited/unlimited
Memory        unlimited/unlimited
Coredump      unlimited/unlimited

2. set permanent ulimit values at /etc/security/limits.conf 

what is ulimit in linux?

Difference between hard & soft ulimits in linux?

To know many file descriptors per process*?

do changes in /etc/security/limits.conf require a reboot?

No but you should close all active sessions windows.

fs.file-max vs ulimit

ulimit shows the per-process maximum open files by user

ulimit -n
1024

(system wide limit) file-max is the maximum File Descriptors (FD) enforced on a kernel level, which cannot be surpassed by all processes without increasing.

root@instance-1:~# cat /proc/sys/fs/file-max
9223372036854775807

temporary change ulimits for user until restart

-n processes

root@instance-1:~# ulimit -n
1024

ulimit -n 2048

root@instance-1:~# ulimit -n 2048
root@instance-1:~# ulimit -n
2048
root@instance-1:~#

What;s the difference between file descriptor and inode limits?

User Level FD Limits

/etc/security/limits.conf

www-data soft nproc 100000

www-data soft nofile 100000

1 2	soft nofile 4096 hard nofile 4096

two file descriptors for each connection increase no file to support highload by os.

File Descriptors (FD)

worker_rlimit_nofile 100000;

nano /etc/sysctl.conf

 

### IMPROVE SYSTEM MEMORY MANAGEMENT ###

# Increase size of file handles and inode cache

fs.file-max = 2097152

# Do less swapping

vm.swappiness = 10

vm.dirty_ratio = 60

vm.dirty_background_ratio = 2

### GENERAL NETWORK SECURITY OPTIONS ###

# Number of times SYNACKs for passive TCP connection.

net.ipv4.tcp_synack_retries = 2

# Allowed local port range

net.ipv4.ip_local_port_range = 2000 65535

# Protect Against TCP Time-Wait

net.ipv4.tcp_rfc1337 = 1

# Decrease the time default value for tcp_fin_timeout connection

net.ipv4.tcp_fin_timeout = 15

# Decrease the time default value for connections to keep alive

net.ipv4.tcp_keepalive_time = 300

net.ipv4.tcp_keepalive_probes = 5

net.ipv4.tcp_keepalive_intvl = 15

### TUNING NETWORK PERFORMANCE ###

# Default Socket Receive Buffer

net.core.rmem_default = 31457280

# Maximum Socket Receive Buffer

net.core.rmem_max = 12582912

# Default Socket Send Buffer

net.core.wmem_default = 31457280

# Maximum Socket Send Buffer

net.core.wmem_max = 12582912

# Increase number of incoming connections

net.core.somaxconn = 65535

# Increase number of incoming connections backlog

net.core.netdev_max_backlog = 65535

# Increase the maximum amount of option memory buffers

net.core.optmem_max = 25165824

# Increase the maximum total buffer-space allocatable

# This is measured in units of pages (4096 bytes)

net.ipv4.tcp_mem = 65535 131072 262144

net.ipv4.udp_mem = 65535 131072 262144

# Increase the read-buffer space allocatable

net.ipv4.tcp_rmem = 8192 87380 16777216

net.ipv4.udp_rmem_min = 16384

# Increase the write-buffer-space allocatable

net.ipv4.tcp_wmem = 8192 65535 16777216

net.ipv4.udp_wmem_min = 16384

# Increase the tcp-time-wait buckets pool size to prevent simple DOS attacks

net.ipv4.tcp_max_tw_buckets = 1440000

net.ipv4.tcp_tw_recycle = 1

net.ipv4.tcp_tw_reuse = 1

Paste this (at the end of the file) to /etc/security/limits.conf (using nano /etc/security/limits.conf) and save it,

nginx           soft    nofile          2097152

nginx           hard    nofile          2097152

www-data        soft    nofile          2097152

www-data        hard    nofile          2097152

Paste this (at the end of the file) to /etc/pam.d/common-session (using nano /etc/pam.d/common-session) and save it,

session required pam_limits.so

Change listen.backlog in /etc/php5/fpm/pool.d/www.conf (using nano /etc/php5/fpm/pool.d/www.conf) and save it,

listen.backlog = 65535 //default to system

Change worker_rlimit_nofile in /etc/nginx/nginx.conf (using nano /etc/nginx/nginx.conf) and save it,

worker_rlimit_nofile 99999;

And finally reboot 🙂

Ephemeral ports – When used as a proxy

Tune file descriptor limits on Linux

Updating Default Kernel Parameter Settings

ubuntu 20.04 server optimization

Disable unnecessary daemons to save memory & cpu

how to apply changes to /etc/security/limits.conf immediately

applies after reboot

without reboot, modify /etc/pam.d/common-session by adding this line at the end of file:

session required pam_limits.so

logout & login