Micron Document




In-kernel web server
──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
top
An in-kernel web server is an unlimited HTTP server that runs in kernel space or equivalent. It is also known as "accelerator".

Contents


──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────

Benefits

Performance: the path taken by data from a source device (i.e. a disk) to a destination device (i.e. a NIC). 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-spaceref-11.

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 (NSA is an acronym for Network Server Accelerator)
Linux: TUX
• Mesibo In-kernel real-time messaging server
Windows NT: http.sys (part of IIS)
SPIN: http
OpenVMS: WASD.trap

See also
References

• endnote-1^1 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