latency report

[Trevor Woerner <twoerner.k@gmail.com>]

I have been performing an investigation to determine the suitability
of using GNU/Linux as a basis for embedded real-time (ish) work and
have prepared a report of my findings. I have made the assumption that
the application logic will be coded as a number of user-space
applications which interact with the hardware. As such, interrupt
latency alone is of little interest; instead I focused more on
measuring the time it takes some data to travel into the target
device, through a bunch of user-space processes (connected via named
FIFOs), then back out the device.

My report currently compares the stock kernel.org 2.6.14 with Ingo's
2.6.14-rt2 patches on two target boards. All preemption settings have
been evaluated. A full explanation of how these tests were conducted,
the various components that were used, the test scenarios that were
created, the results I measured, kernel configurations, and required
patches are included in the report.

This project's index can be found here ("Linux Latency"):
http://geek.vtnet.ca/embedded.html

All of the tools, scripts, and code I wrote to measure and generate
this report can be found in the project tarball (~1.7MB bzip2):
http://geek.vtnet.ca/embedded/LatencyTests/latencytests-3.2.1.tar.bz2

The report is here in html:
http://geek.vtnet.ca/embedded/LatencyTests/html/index.html

Code documentation (in various formats) and a PDF of the report are
also available.

Ingo Molnar has been incredibly helpful and provided an enormous
amount of initial feedback and suggestions; thank you.

Please CC me on any replies.
Thank you.
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