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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

#21

Post by bboreham »

blattimwind wrote: post #10
notacoward wrote: post #4

To answer the question in the OP: yes, the processor cache might be more susceptible than RAM, if the RAM is ECC. I've heard many stories about bit-flips causing serious problems at higher-elevation sites. Apparently a major installation at either NCAR or UCAR was delayed by a month fighting such problems. While I haven't actually confirmed any of these stories first hand, I've heard enough to believe that a little p…

Internal data buses and caches are typically ECC'd. In fact, DRAM and the memory bus are most likely the only non-ECC parts in desktop computers.

The way I remember it, when this happened on our Sun E10Ks, the RAM was ECC but the cache was not.

Maybe I misremember. It was 20 years ago.

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

#23

Post by ip26 »

jimrandomh wrote: post #12
fpgaminer wrote: post #11

So ... here's what I'm thinking, as a complete layman with respect to how radiation affects memory devices. RAM is DRAM, i.e. dynamic RAM. It has to get automatically refreshed relatively frequently. So, maybe (again, me being a layman) what happens is that usually gamma rays hit a DRAM cell, but haven't imparted enough energy to cause a flip. A millisecond later the cell gets refreshed erasing what little influence…

No, SRAM doesn't work that way. DRAM needs refreshing because it's made out of capacitors; if left alone, their charge will stay the same. Whereas SRAM is made of flip-flops; if the charge in an SRAM cell moves towards an intermediate state in between 0 and 1, it will naturally move back to 0 or 1 (whichever is closer) with no refreshing needed, by virtue of its structure.

DRAM needs refreshing because it's made out of capacitors; if left alone, their charge will stay the same.

No; capacitors slowly leak and lose their charge. This is why DRAM remains powered when your computer sleeps, eternally refreshing.

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

#25

Post by jermaustin1 »

nategri wrote: post #15

A pedantic point (good thing I'm on HN), but I wonder if they didn't actually mean muons and not gamma rays?

I doubt think the programmer knew one way or the other, just doing what they were told by the manufacturer, and gamma ray is probably easier to explain to anyone after the 1950s/60s than muon.

I mean after all, did any superhero get their powers from muons?

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

#26

Post by amichal »

spullara wrote: post #19

If you don't believe in bit flips, try this! http://dinaburg.org/bitsquatting.html I did that for a bit on cloudfront.net and got dozens of them in a short amount of time.

bitflips are also single char typos in ascii. I'm guessing that is what you saw

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

#27

Post by 21 »

nategri wrote: post #15

A pedantic point (good thing I'm on HN), but I wonder if they didn't actually mean muons and not gamma rays?

Apparently 95% of "bit flipping cosmic rays" are neutrons:

> At the Earth's surface approximately 95% of the particles capable of causing soft errors are energetic neutrons with the remainder composed of protons and pions.

https://en.wikipedia.org/wiki/Soft_error#Cosmic_rays_creatin...

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

#28

Post by Kenji »

amichal wrote: post #26
spullara wrote: post #19

If you don't believe in bit flips, try this! http://dinaburg.org/bitsquatting.html I did that for a bit on cloudfront.net and got dozens of them in a short amount of time.

bitflips are also single char typos in ascii. I'm guessing that is what you saw

Read the article before commenting, please. He addressed that.

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

#29

Post by tjoff »

spullara wrote: post #19

If you don't believe in bit flips, try this! http://dinaburg.org/bitsquatting.html I did that for a bit on cloudfront.net and got dozens of them in a short amount of time.

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 caused issued.

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