Boost High‑Load PHP Performance: Essential Linux Tuning Tips

High‑Load PHP Tuning

Linux tuning for PHP

Adjust file descriptor limits

# ulimit -n 1000000
# vi /etc/security/limits.conf
# Setting Shell Limits for File Descriptors
*  soft nofile 1000000
*  hard nofile 1000000

Disable atime updates on the PHP code partition

# vi /etc/fstab

For example, the partition containing PHP code: /dev/sdb1 ext4 errors=remount-ro 0 1 Change to:

/dev/sdb1   ext4    noatime,nodiratime,errors=remount-ro  0  1

Store temporary files on tmpfs

When handling many small image uploads (e.g., user avatars), using a memory‑based tmpfs reduces I/O overhead, but it is unsuitable for very large files such as videos.

# vi /etc/fstab
tmpfs   /tmp   tmpfs   defaults,nosuid,noatime 0 0

PHP configuration tuning

php.ini tuning

# vi php-app.ini
[PHP]
engine = On
expose_php = Off

max_execution_time = 5
memory_limit = 256M
error_reporting = E_ALL & ~E_DEPRECATED
display_errors = Off
display_startup_errors = Off
html_errors = Off
default_socket_timeout = 5

file_uploads = On
upload_tmp_dir = /tmp/php
upload_max_filesize = 50M
post_max_size = 50M
max_file_uploads = 20

date.timezone = 'Asia/Shanghai'

Note that max_execution_time is set to only 5 seconds. For a fast web application we aim for request latency of 300‑500 ms; any request exceeding 5 seconds usually indicates a problem.

PHP‑FPM tuning

# vi php-fpm.conf
[my_app]
;FastCGI/PHP‑FPM using UNIX sockets
listen = /data/my_app/tmp/php.sock
listen.backlog = 300
user = www
group = www
pm = dynamic
; Estimate pm.max_children = (MAX_MEMORY - 500MB) / 20MB
pm.max_children = 100
; Recommended as 10% of max_children
pm.start_servers = 10
pm.min_spare_servers = 5
pm.max_spare_servers = 15
pm.max_requests = 1000
pm.status_path = /php_status

request_terminate_timeout = 0
request_slowlog_timeout = 0
slowlog = /data/my_app/logs/slow.log