I use a bunch of nginx + php-fpm on a server running Debian Lenny x86_64. Sometimes the PHP-FPM's processes loads all 8 cores at 100% and this load does not fall until to forced restart PHP-FPM. How can I determine what is the problem of such jumps load? In the PHP-FPM's logs is nothing unusual. Version of PHP - 5.3.3.
This might actually be a problem with your application, not php-fpm itself, so you may want to look there first, as well as double check your current config files for php-fpm, and make sure you don't have high I/O wait on your system.