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For a brief period, the Windows kernel tried to deal with gamma rays

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Re: For a brief period, the Windows kernel tried to deal with gamma rays

#111

Post by posix_me_less »

oh_sigh wrote: post #104
skunkworker wrote: post #88

Earlier quoted context omitted.

An article I read awhile ago addressed an interesting correlation between transistor process size, the physical size of the dram module and the expected failure rates. "As transistor sizes have shrunk, they have required less and less electrical charge to represent a logical bit. So the likelihood that one bit will "flip" from 0 to 1 (or 1 to 0) when struck by an energetic particle has been increasing. This has been…

How much shielding would it take to prevent most of these energetic particles from reaching the important bits?

It depends on what you mean by "most". Even shielding 95% may not be sufficient, if the remaining 5% is too strong. It is a tradeoff - the thicker the plating, the better protection, but beyond some limit the plating gets too heavy, which is very costly especially when it is to be put in orbit.

Re: For a brief period, the Windows kernel tried to deal with gamma rays

#112

Post by JdeBP »

herogreen wrote: post #24

Could it be that the manufacturer was aware of a bug and chosed to circumvent it by using gamma rays as a pretext ?

That's the implication of the mentions of processor steppings, that almost everyone is ignoring in favour of discussing a more exciting subject. (-:

Re: For a brief period, the Windows kernel tried to deal with gamma rays

#113

Post by biggerfisch »

Nokinside wrote: post #53
datenwolf wrote: post #49

Invalidating the caches is kind of a cringe inducing approach on this (actual) problem. Especially in HPC radiation related single event upsets have become a real problem. If you do the math, all the silicon area devoted to memory (DRAM, caches, registers) adds up, and what you've got is essentially particle detector. Compared to the effective volume of a purpose designed one (ATLAS, CMS, Super Kaminokade, etc.) rath…

Could physicists and astronomers use all this distributed particle detection for research? Like a app in a phone or desktop that sends reports back with location and time information.

Probably not, due to the low fidelity of any data from this. "real" particle detectors can trace the decay chain, momentum changes, precise energy levels, etc. Processor cache flips etc can only say "a particle with energy >= X was here", which isn't super useful given the relative frequency of occurrence.

Re: For a brief period, the Windows kernel tried to deal with gamma rays

#114

Post by atq2119 »

zaarn wrote: post #110
atq2119 wrote: post #107

Earlier quoted context omitted.

Yes, it is. That's what makes it fundamentally different from DRAM, which isn't being continuously refreshed, which is why the memory controller has to manually refresh DRAM at frequent intervals. DRAM has much simpler cells, at the cost of more complex control logic. I recommend you just take a look at Wikipedia or something for an explanation of SRAM. Each bit is typically implemented using six transistors, four of…

There is no continuous "refresh". The circuit is bistable which means that the system has two states in which, once reached, it will remain until some energy is expended to change that. Imagine it like two valleys with a hill between. Rolling a ball from the OFF valley to the ON valley requires some energy. If it's not enough the ball rolls back into the valley it's currently in. The process is entirely analog, ie, t…

That seems awfully nitpicky in this context. Look at russdill's comment, then look at the throwaway, which is reasonable to interpret as stating that DRAM is being continuously refreshed - which it isn't, it happens at discrete intervals.

Anyway, what you're writing isn't wrong but I'd say misses the context of the conversation a bit :)

(Also, it's a great example of mansplaining...)

Re: For a brief period, the Windows kernel tried to deal with gamma rays

#115

Post by zaarn »

atq2119 wrote: post #114
zaarn wrote: post #110

Earlier quoted context omitted.

There is no continuous "refresh". The circuit is bistable which means that the system has two states in which, once reached, it will remain until some energy is expended to change that. Imagine it like two valleys with a hill between. Rolling a ball from the OFF valley to the ON valley requires some energy. If it's not enough the ball rolls back into the valley it's currently in. The process is entirely analog, ie, t…

That seems awfully nitpicky in this context. Look at russdill's comment, then look at the throwaway, which is reasonable to interpret as stating that DRAM is being continuously refreshed - which it isn't, it happens at discrete intervals. Anyway, what you're writing isn't wrong but I'd say misses the context of the conversation a bit :) (Also, it's a great example of mansplaining...)

I'm not mansplaining, I don't even know who you are. You don't know who I am. I'm attempting to make the comment digestible for a broader audience and not only for you. You're not alone on this website. I'm sorry for doing that then.

Tbh I find that accusation incredibly rude.

Re: For a brief period, the Windows kernel tried to deal with gamma rays

#116

Post by kingosticks »

jhallenworld wrote: post #103
tjoff wrote: post #29

Earlier quoted context omitted.

Bit flips in network surely is many orders of magnitude worse than in cache/memory bit flips? And I doubt it has to do with gamma rays. Those with poor or long distance DSL do see a big increase in errors. And while hopefully getting rarer now home routers could easily overheat and introduce errors as soon as they saw more than usual traffic. We recently had issues with the power supply for our router and it also cau…

So Ethernet is protected by CRC which is quite good, but it is stripped at both ends and I would not trust the routing chips at all. Some core routers used low reliability FPGAs for example..

If you require data integrity you cannot rely on ethernet's FCS. Personally I trust the core router far more than I trust the cheaper stuff around it, particularly the stuff my ISP gave me for 'free'.

Re: For a brief period, the Windows kernel tried to deal with gamma rays

#117

Post by Dylan16807 »

zaarn wrote: post #115
atq2119 wrote: post #114

Earlier quoted context omitted.

That seems awfully nitpicky in this context. Look at russdill's comment, then look at the throwaway, which is reasonable to interpret as stating that DRAM is being continuously refreshed - which it isn't, it happens at discrete intervals. Anyway, what you're writing isn't wrong but I'd say misses the context of the conversation a bit :) (Also, it's a great example of mansplaining...)

I'm not mansplaining, I don't even know who you are. You don't know who I am. I'm attempting to make the comment digestible for a broader audience and not only for you. You're not alone on this website. I'm sorry for doing that then. Tbh I find that accusation incredibly rude.

The explanation you were replying to was more digestible than yours.

Your definition of "refresh" is unhelpfully specific and not particularly correct. The circuit that "looks at a voltage and freshens it up", also known as an amplifier, is just a transistor or pair of transistors.

Re: For a brief period, the Windows kernel tried to deal with gamma rays

#118

Post by zaarn »

Dylan16807 wrote: post #117
zaarn wrote: post #115

Earlier quoted context omitted.

I'm not mansplaining, I don't even know who you are. You don't know who I am. I'm attempting to make the comment digestible for a broader audience and not only for you. You're not alone on this website. I'm sorry for doing that then. Tbh I find that accusation incredibly rude.

The explanation you were replying to was more digestible than yours. Your definition of "refresh" is unhelpfully specific and not particularly correct. The circuit that "looks at a voltage and freshens it up", also known as an amplifier, is just a transistor or pair of transistors.

An amplifier doesn't look at voltage and "freshens it up", in an SRAM cell, the amplifier is running in clipping and unlike a DRAM cell requires no clocking, only supply voltage. A pair of transistors does not behave like that since they operate over current. You need two inverting amplifier, which is more complex and isn't simply "looking at voltage to freshen in up".

If my attempt to make everything more digestible failed in your opinion, then I guess that is it, it's your opinion on the matter.

Re: For a brief period, the Windows kernel tried to deal with gamma rays

#119

Post by Dylan16807 »

zaarn wrote: post #118
Dylan16807 wrote: post #117

Earlier quoted context omitted.

The explanation you were replying to was more digestible than yours. Your definition of "refresh" is unhelpfully specific and not particularly correct. The circuit that "looks at a voltage and freshens it up", also known as an amplifier, is just a transistor or pair of transistors.

An amplifier doesn't look at voltage and "freshens it up", in an SRAM cell, the amplifier is running in clipping and unlike a DRAM cell requires no clocking, only supply voltage. A pair of transistors does not behave like that since they operate over current. You need two inverting amplifier, which is more complex and isn't simply "looking at voltage to freshen in up". If my attempt to make everything more digestible…

> An amplifier doesn't look at voltage and "freshens it up"

Sure it does, as long as you set the proper bias and use a definition of "fresh" that makes sense for digital signals.

> unlike a DRAM cell requires no clocking

Yes, that's why it's 'continuous'.

> You need two inverting amplifier

You don't need to use that design. It just happens to have reasonable size and leakage characteristics.

> more complex and isn't simply "looking at voltage to freshen in up"

That circuit is a hundred times simpler than the DRAM refreshing circuit you used those words to describe!

Re: For a brief period, the Windows kernel tried to deal with gamma rays

#120

Post by zaarn »

Dylan16807 wrote: post #119
zaarn wrote: post #118

Earlier quoted context omitted.

An amplifier doesn't look at voltage and "freshens it up", in an SRAM cell, the amplifier is running in clipping and unlike a DRAM cell requires no clocking, only supply voltage. A pair of transistors does not behave like that since they operate over current. You need two inverting amplifier, which is more complex and isn't simply "looking at voltage to freshen in up". If my attempt to make everything more digestible…

> An amplifier doesn't look at voltage and "freshens it up" Sure it does, as long as you set the proper bias and use a definition of "fresh" that makes sense for digital signals. > unlike a DRAM cell requires no clocking Yes, that's why it's 'continuous'. > You need two inverting amplifier You don't need to use that design. It just happens to have reasonable size and leakage characteristics. > more complex and isn't…

I described no DRAM refreshing circuit, I describe a SRAM cell, I don't believe that definition of fresh is suitable for the discussion nor is it fitting when talking about SRAM, I also never said it wasn't continuous, ie linear, I did disagree with the wording that made it sound like there is a refresh process that happens repeatedly.
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