Archive for the ‘ Linux ’ Category
I have recently been debugging Apache2/PHP5 (running with mpm_prefork what turned out to be important later) server suffering for very high load spikes. Load was completely CPU related, there was almost no IO operations performed during peak times and surprisingly significant part of CPU time was spent in the kernel (about 20%) mode. [ READ MORE ]
I had a need to route a particular process’ traffic through remote server in order to be let in by third parties firewalls. Most flexible way to do so in was to mark the traffic per account basis. Fortunately Linux allows you to do so using owner match in iptables. In my instance user account [ READ MORE ]
Some time ago I came across a need to generate real time statistics of how many emails do our Exim installations send per second. Didn’t want to go into reconfiguring exim itself, thus I wrote a simple C program, that follows syslog generated file, does little parsing on a timestamp, and writes stats to disks [ READ MORE ]