How to enable JIT for OPcache in PHP 8

Introduction

A Just-In-Time (JIT) compiler was included in PHP 8's core, but it is disabled by default. This article provides the steps to enable it with ZendOPcache.

Procedure

Please note that in the following procedure, "##" must be replaced by the PHP version without the decimal point.

1. Access the server's command line as the 'root' user via SSH or "Terminal" in WHM.
2. Install the ZendOPcache package for the desired PHP version.
   • RHEL-based OSes

     dnf install ea-php##-php-opcache -y

   • Ubuntu

     apt install ea-php##-php-opcache -y

3. Open /opt/cpanel/ea-php##/root/etc/php.ini in your preferred text editor.
4. Add the following to the end of the file.
   • PHP 8.0-8.3

     opcache.jit_buffer_size=16M

   • PHP 8.4

     opcache.jit_buffer_size=16M

     opcache.jit=tracing

5. Save the changes and exit the text editor.

Additional resources

OPcache Runtime Configuration

OPcache opcache_get_status