In this section, we present experimental methodology used to compare user-mode Web server performance with kernel-mode implementations based on the AFPA framework described in the previous section. The goal of the methodology is to establish a baseline for user-mode performance and compare the best performing user-mode approaches with Web servers based on AFPA. We compare several user-mode and kernel-mode HTTP servers: Apache 1.3.9 [6], Zeus 3.3.5 [7], IIS 5.0 [8], and two experimental Web servers referred to as Howl. We also consider other kernel-mode Web servers: kHTTPd [17] and TUX [18] on Linux, and Microsoft's SWC 2.0 [16].