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

Contents

β€’ Benefits
β€’ Drawbacks
β€’ See also
β€’ References

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Benefits

β€’ 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.
β€’ Scalability: with respect to number of simultaneous clients. Event notification of comparable scalability seems unlikely in user-spaceref-11.

Drawbacks

β€’ Security: Kernel processes run with unlimited privileges.
β€’ Portability. Every kernel needs a specific implementation route.
β€’ Reliability. Failure in the webserver may crash the OS.

Implementations

β€’ illumos/Solaris: NCAkmod aka Network Cache and Accelerator (NCA) kernel module
β€’ HP-UX: NSAhttp (NSA is an acronym for Network Server Accelerator)
β€’ Linux: TUX
β€’ Mesibo In-kernel real-time messaging server
β€’ Windows NT: http.sys (part of IIS)
β€’ SPIN: http
β€’ OpenVMS: WASD.trap

See also
References

β€’ endnote-1^1 CITI_TR_00-4
β€’ 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