EMC2's Latency-test on 2.6.22-12-rt
The "port" consists of changing sim_rtapi to use a mostly-pthreads API instead of pth, making it setuid, and making it able to do I/O.
latency-test 500us - reports latencies of up to about 32uS on a period of 500uS, and a scope on the parport confirms it.
This is promising for machines with only a servo-thread, but discouraging for software step generation.
To try it out, install gutsy beta and kernel 2.6.22-12-rt. Patch the TRUNK of emc with the patches below, and configure with --enable-simulator --enable-run-in-place. The "sudo make setuid" step is now required, and the "sim" name becomes increasingly inaccurate.
Since rtai offers a "mostly posix API" called lxrt, these changes also offer a way forward if the kernel-mode rtai APIs start to bitrot.
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(originally posted on the AXIS blog)
Entry first conceived on 27 September 2007, 17:02 UTC, last modified on 15 January 2012, 3:46 UTC
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