[sr-dev] [kamailio/kamailio] performance regression related to new TCP connection tracking feature with a high number of connections (Issue #3759)

### Description On systems with a high number of TCP sessions there can be a significant performance regression observed, probably related to the newly added TCP connection tracking feature. ### Troubleshooting #### Reproduction No special configuration is necessary, just install the latest 5.7.x release, e.g. 5.7.3 on a production system with a lot of clients connected over TCP or TLS. You need to have a large number of clients connected to be able to observe the regression. For a high number of connections (e.g. more then 20.000 up to 30.000 connections) the Kamailio servers uses about 30% to 50% more CPU as with the old version. #### Debugging Data Two graphs were attached to this issue. The first shows the CPU load before (less load) and after the upgrade (increased load). The second is a flamegraph that shows that over 80% of the CPU time is spent in the newly added function tcp_connection_limit_srcip(). <img width="372" alt="cpu-load-before-after" src="https://github.com/kamailio/kamailio/assets/6481937/ec92c41b-25e2…  Most of the CPU time is spend in the TCP main process, as expected. #### Log Messages No special log messages could be observed. #### SIP Traffic ### Possible Solutions The TCP limit feature should probably be optimized to not cause such a large performance regression. It should be also possible to deactivate it completly and therefore getting a comparable performance as before the feature addition. ### Additional Information Kamailio 5.7.3 and probably also git master version. * **Operating System**: Debian 11, Debian 12 -- Reply to this email directly or view it on GitHub: https://github.com/kamailio/kamailio/issues/3759 You are receiving this because you are subscribed to this thread. Message ID: &lt;kamailio/kamailio/issues/3759(a)github.com&gt;