Update on Kamailio performance - 100 calls per CPU core per GHz
In 2007, TransNexus published a performance study of SIP Express Router(SER) compared to OpenSER. Kamailio is a fork from the OpenSER project, which was a fork of the SER project. Since then Kamailio, and SER have merged to create the SIP Router project.
In 2007, we found that the total number of calls per second that could be routed by OpenSER was 85 calls, multiplied by the number of CPU cores, multiplied by the CPU clock speed in GHz. For example, OpenSER running on a dual core CPU with a 2 GHz clock could route a total of 85*2*2=340 calls per second. We ran our test on a Intel Xeon 5140 2.33 GHz CPU.
On September 13, 2012, Mino Haluz reported on the SIP Router - Kamailio mailing list that he found Kamailio can route approximately 100 calls per second per CPU core per GHz of clock speed. This 15% plus perfromance improvement is good news and probably a result of many incremental improvements in CPU and server hardware. His testing was performed on an Intel E5504 Xeon 4MB cache 2GHz.