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Real time for what?Real time for what?Posted Nov 13, 2012 14:29 UTC (Tue) by epa (subscriber, #39769)In reply to: Real time for what? by man_ls Parent article: LCE: Realtime, present and future
My guess would be systems which are real-time but not safety-critical. In principle, Linux is too complex for use in systems where a bug can cause deaths. In practice I daresay there will be those using it anyway.
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Real time for what? Posted Nov 13, 2012 16:19 UTC (Tue) by gregkh (subscriber, #8) [Link]
Hm, like MRI machines? Air traffic control systems? Airplane flight navigation? Coal fired power generators? Windmill controls? Yacht stabilizers? Spacecraft control systems? Laser welding robots? High-speed milling machines?
I could go on and on. Linux is used for lots of things like this, and has been for years (something like over 85% of the US power production is controlled directly by Linux machines). A lot of these systems use the real-time patches, and others don't, but to think that Linux isn't being used in these type of situations is wrong.
Real time for what? Posted Nov 15, 2012 11:34 UTC (Thu) by epa (subscriber, #39769) [Link]
Hmm, you're right. I would draw a distinction between the software running on the air traffic controller's desktop (which has often been Unix for decades now) and the microcontroller which controls the air intake to the engines. The former has fairly relaxed real-time requirements (the display has to update, but once a second might be acceptable) and I would call it 'soft safety-critical'. The software running on your doctor's desktop PC could kill you if it displays the wrong notes and causes the doctor to prescribe the wrong medicine - yet this is not normally an application considered safety-critical where special software methods must be used to guarantee correctness. By contrast, a failure of the jet engine microcontroller (assuming it has one, I am speculating) can cause instant disaster.
Real time for what? Posted Nov 16, 2012 18:29 UTC (Fri) by jtc (subscriber, #6246) [Link]
" The software running on your doctor's desktop PC could kill you if it displays the wrong notes and causes the doctor to prescribe the wrong medicine - yet this is not normally an application considered safety-critical where special software methods must be used to guarantee correctness."
It's also requires neither a soft nor hard real-time kernel. :-)
[On a complete tangent: Is anyone else getting completely sick of that constantly changing Perforce ad. that adorns the top and upper right side of almost every page on LWN. I find it quite distracting and have to move another window to cover the right side of the page each time I open a new lwn page, so that I don't have the ad. screaming at me all the time while I'm reading! They've been running this ad. for many weeks - it's about time the found a new sponsor. Argghh!]
Real time for what? Posted Nov 16, 2012 18:40 UTC (Fri) by dlang (✭ supporter ✭, #313) [Link]
I believe that as a subscriber you can disable advertisements.
LWN doesn't go after individual sponsors, they subscribe to an advertisement service that puts the ads in place based on their own criteria.
Real time for what? Posted Nov 16, 2012 19:12 UTC (Fri) by Trelane (subscriber, #56877) [Link]
> I believe that as a subscriber you can disable advertisements.
At the Professional Hacker level or above:
Real time for what? Posted Nov 16, 2012 21:06 UTC (Fri) by jtc (subscriber, #6246) [Link]
"At the Professional Hacker level or above:"
Damn. I'm a "starving hacker". I'll have to upgrade once I find a job.
Thanks for the info.
Real time for what? Posted Nov 16, 2012 21:07 UTC (Fri) by Trelane (subscriber, #56877) [Link]
NP. Glad you found it informative. :)
Real time for what? Posted Nov 13, 2012 16:41 UTC (Tue) by dashesy (subscriber, #74652) [Link]
Well not if they are audited for a very narrow use case on dedicated long-life hardware, and fixed on a certain Kernel version without updates and with minimal applications (i.e. instruments).
BTW, one more example I can add is DAQs.
Real time for what? Posted Nov 19, 2012 3:20 UTC (Mon) by mathstuf (subscriber, #69389) [Link]
I assume that "DAQ" is meant to be "DAW" (digital audio workstation)?
Real time for what? Posted Nov 19, 2012 15:36 UTC (Mon) by dashesy (subscriber, #74652) [Link]
Actually I meant Data Acquisition (DAQ) with additional output channels.
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