4 ms·

Doesn't radiation mostly cause random one-off errors rather than permanent defects? If so, then if the rad-harden stuff is 100x slower (which I think is approxi

Doesn't radiation mostly cause random one-off errors rather than permanent defects? If so, then if the rad-harden stuff is 100x slower (which I think is approximately right?), it is almost certainly better to use error correction on non-rad-hardened hardware.

londons_explore 6y ago
Many types of bit error are not recoverable without a full system reset. It isn't a matter of a simple "this bit in ram got corrupted", but more "this floating point unit has got into a state where it will not produce a result, and will therefore hang the entire processor". Therefore boot time becomes critical - if you end up rebooting due to bit errors multiple times per second, you can't afford to wait for Linux to start up each time...
- spockz 6y ago
  Well I suppose they do not have to load all the kernels and drivers that Linux provides today. I wonder how one could use micro kernels to further improve startup time and have a mini distributed OS/kernel for each component.
- dawnerd 6y ago
  And that’s why it’s wise to have multiple systems running at the same time, if one errors you still hopefully have another online. There’s a reason airplanes and now cars are designed this way. I’m sure they’re working towards this too.
- ajuc 6y ago
  Run 9 systems in parallel and reset the ones that give less common results or no results at all. You still have 10% the surface area, power usage and weight and 10 times the speed of the radiation hardened ones.
- jessriedel 6y ago
  This is a problem with floating point operations happening at a lower level than the error correction you're imagining. In principle, that's not at all necessary. Are you arguing that it's infeasibly expensive to design a chip with operations that are error correctable?
  - londons_explore 6y ago
    It's possible - but you'll end up reinventing nearly every step of the IC design process, which will cost a lot.
ejolto 6y ago
In addition to SEUs (single event upsets) which are bit flips, there are also the following Single Event Effects (See) that are destructive: - Single Event Burnout, SEB - Single Event Gate Rupture, SEGR - Single Event Latch-up, SEL these can be recoverable In addition there are also Total Ionizing Dose (TID) Effects https://radhome.gsfc.nasa.gov/radhome/tid.htm https://radhome.gsfc.nasa.gov/radhome/tid.htm
- jessriedel 6y ago
  Sure, no doubt they occur. But at what rate?

londons_explore 6y ago

Many types of bit error are not recoverable without a full system reset. It isn't a matter of a simple "this bit in ram got corrupted", but more "this floating point unit has got into a state where it will not produce a result, and will therefore hang the entire processor". Therefore boot time becomes critical - if you end up rebooting due to bit errors multiple times per second, you can't afford to wait for Linux to start up each time...

spockz 6y ago
Well I suppose they do not have to load all the kernels and drivers that Linux provides today. I wonder how one could use micro kernels to further improve startup time and have a mini distributed OS/kernel for each component.
dawnerd 6y ago
And that’s why it’s wise to have multiple systems running at the same time, if one errors you still hopefully have another online. There’s a reason airplanes and now cars are designed this way. I’m sure they’re working towards this too.
ajuc 6y ago
Run 9 systems in parallel and reset the ones that give less common results or no results at all. You still have 10% the surface area, power usage and weight and 10 times the speed of the radiation hardened ones.
jessriedel 6y ago
This is a problem with floating point operations happening at a lower level than the error correction you're imagining. In principle, that's not at all necessary. Are you arguing that it's infeasibly expensive to design a chip with operations that are error correctable?
- londons_explore 6y ago
  It's possible - but you'll end up reinventing nearly every step of the IC design process, which will cost a lot.

ejolto 6y ago

In addition to SEUs (single event upsets) which are bit flips, there are also the following Single Event Effects (See) that are destructive: - Single Event Burnout, SEB - Single Event Gate Rupture, SEGR - Single Event Latch-up, SEL these can be recoverable In addition there are also Total Ionizing Dose (TID) Effects https://radhome.gsfc.nasa.gov/radhome/tid.htm https://radhome.gsfc.nasa.gov/radhome/tid.htm

jessriedel 6y ago
Sure, no doubt they occur. But at what rate?