Hi, I've been trying to configure an Apache server and ATS on a host. For us, the latency matters more than RPS/QPS.
We've observing a huge spike in latency for a small number of requests. Typically, the 99.99%-ile are in tens to hundreds of ms. The 100%-ile is often couple of single digit seconds. Where as the 50%-ile is less than 2 ms and 99.9%-ile is nearly 5ms. Above %-iles are all based on observations/measurements from clients side. In general, a unloaded server takes around 2 ms to process a request (e.g. Time spent in the Apache module processing the request). In terms of RPS, the best so far has been around 2.2K RPS with 16 clients programs and Apache (2.2) server with max client set to 31. We're using persistent connections between the client and the ATS and transient/non-persistent connections between ATS and Apache. Apache processes are configured to served unlimited number of requests. It uses preform MPM. [ET_NET 0] uses up to 80% or more cpu (based on top). The 99.9%-ile latencies worse if the number of clients exceed the no of Apache processes. This is the first time I'm experimenting with ATS. Pointers towards keeping the latency in check and maximizing the performance without impacting the latency will be highly appreciated. Currently, the max cup utilization is ~25%. Please note, I want to use ATS only as a reverse proxy and I don't intend to use any other functionality (like caching etc). Thanks, Kanishka
