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RTEMS vs. VxWorks
- Date: Mon, 22 Jan 2001 12:24:59 -0500 (EST)
- From: gregory.menke at gsfc.nasa.gov (gregory.menke at gsfc.nasa.gov)
- Subject: RTEMS vs. VxWorks
> > Has anyone had the opportunity to compare the task switch times and
> > interrupt latencies of these two systems? I have a gut feeling that
> > RTEMS is faster, but can someone provide supporting data for this
> > belief?
We've used a program called POSIXPERF to compare RTEMS to Lynx on a
PPC 750 running at 233mhz. The author of the benchmark got data on
Lynx and vxWorks on a Pentium 233mhz, and using the Lynx metrics as a
baseline, we estimate RTEMS is <extremely> close to vxWorks Tornado 2
in performance. We've not done more detailed analysis, so its
possible RTEMS is faster- but its certainly close.
By "performance", we mean "work done in unit time". Or, application
work done in a particular duration- this is speaking to OS
efficency/overhead in threads, queues and semaphores. This isn't
exactly task switching or interrupt latency, but its pretty close.
I suspect variations in bsp will cause performance differences with
both RTEMS and vxWorks on a given platform. We're getting a RTEMS bsp
for our moderately ancient MIPS satellite flight board, I know for a
fact that our vxWorks bsp has some extremely dreadful fp context
switch overhead- so its possible RTEMS will be a big benefit here- its
fp context code is far more civilized.
At some point in the next 2 weeks or so we'll publish what benchmark
data we have to date on our project pages;
Posixperf is a good RTEMS demo project in several ways, so pretty soon
I'm going to upload an RTEMS-centric version of it- the author has
told me he'd be glad to have that done. Just takes a little time....