Julia bindings for POSIX Clock.
From Julia REPL, run
Pkg.clone("https://github.com/ibadr/POSIXClock.jl")
The initial scope of this Julia package is to expose PREEMPT_RT capabilities to Julia users. The long-term goal is to provide cross-platform wrapping of POSIX clock_*() functions similar to node-posix-clock and posix-timer.
For real-time performance, it is recommended to use in-place operations and to pre-allocate all needed variables prior to entering the real-time section. Also, use CLOCK_MONOTONIC in order to avoid jumps related to changing the system time. Typical usage example is as follows
import POSIXClock; CLK=POSIXClock
function main() # it is important to wrap your code in a function to avoid
# unnecessary memory allocations
t=CLK.timespec(0,0) # pre-allocate
gc_enable(false) # temporarily disable the GC
# enter real-time section
CLK.gettime!(t,CLK.CLOCK_MONOTONIC) # get current Linux time
@time for n in 1:10000
CLK.nanosleep!(t,300000) # increment t by 300us and sleep until that time (absolute time)
end # the loop time should be around 3 sec
# exit real-time section
gc_enable(true) # enable the GC
end
main() # execute the main function
See the examples directory. The next example latency plot was obtained by running Julia as a real-time process on PREEMPT_RT Linux kernel, then including the "rt_histogram.jl" file from the examples folder. This example plot was generated on Ubuntu 16.04 running a custrom PREEMPT_RT Linux kernel v4.4.12-rt19 with CPU frequency scaling disabled. Julia was run on a dedicated processor core (using taskset & isolcpus=1 kernel command line) on a dual-core Intel Celeron processor based on SandyBridge architecture, with elevated SCHED_FIFO priority 50 (using chrt). The first CPU core was stress-loaded using the stress utility.
