In-kernel web server
An in-kernel web server is an unlimited HTTP server that runs in kernel space or equivalent. It is also called "accelerator".
Benefits
- Performance. The path taken by data from disk to network. Proper asynchronous zero-copy interfaces would make this available from user-space.
- Scalability with respect to number of simultaneous clients. Event notification of comparable scalability seems unlikely in user-space1.
Drawbacks
- Security: Kernel processes run with unlimited privileges.
- Portability. Every kernel needs a specific implementation route.
- Reliability. Failure in the webserver may crash the OS.
Implementations
- illumos/Solaris: NCAkmod aka Network Cache and Accelerator (NCA) kernel module
- HP-UX: NSAhttp
- Linux: TUX
- Windows NT: http.sys (part of IIS)
- SPIN: http
- OpenVMS: WASD.trap
See also
- Comparison of lightweight web servers
- Comparison of web server software
References
- ^1 CITI_TR_00-4
- High-Performance Memory-Based Web Servers: Kernel and User-Space Performance. Philippe Joubert, Robert B. King, Rich Neves, Mark Russinovich, John M. Tracey. IBM. T. J. Watson Research Center
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