4 ms·

Why not? There are CPUs being designed that do floating point math “wrong” but faster… I’m sure many people would use RAM that’s cheaper and faster but row ham

by _3u10 4y ago

Why not? There are CPUs being designed that do floating point math “wrong” but faster… I’m sure many people would use RAM that’s cheaper and faster but row hammer vulnerable. Just as many people drive cars with engines that will break if driven at redline for long periods of time. It’s not like row hammer is a realistic use case. No algorithm depends on row hammer access patterns. Just like people don’t buy cars to bounce off the rev limiter.

mort96 4y ago
"Why not" what? Why we don't get the option to buy rowhammer-resistent RAM? I don't know, ask manufacturers and resellers I suppose? I don't make the spec sheets.
- sroussey 4y ago
  If you run a server farm, you absolutely know these things. And you are using ECC based RAM.
  - mort96 4y ago
    Most of us don't run server farms.
    - sroussey 4y ago
      Most of us don’t care about rowhammer then either.
- _3u10 4y ago
  You have the option, you just choose not to pay for ECC ram.
suavesito 4y ago
That is fundamentally different. Floating point computation not nearly as always needs to be done to the last digit of precision. For a lot of application 10^-8 is more than enough, for some even less digits might be enough. But fast calculation might be a lot more important if you're in a real time scenario or if you're doing HPC. On the other hand, is not only row hammer attacks that cause bit flips, random bit flips happens, cosmic ray or decline of radioactive particles might cause one. And there is _no way_ to know if one happened on non ECC RAM (I know, ECC only reduces the probability of not noticing it, but it reduces that probability), and given that there is not way to respond. If one random bit flip happens, best case nothing happens. If you are unlucky, maybe your system will crash. If you are really unlucky your data might end up corrupted and the OS might not even be able to detect it. Or maybe you were running a 100 hours calculation, and it might go wrong in the first minutes because of a bit flip and your simulation is ruined. Floating point operations is about precision, witch can be studied and decided based on the needs of the application, bit flips are about data corruption.
- _3u10 4y ago
  I'm guessing more crashes occur because of bugs in software or RAM / CPUs that are already damaged than row hammering.

by _3u10 4y ago

mort96 4y ago

"Why not" what? Why we don't get the option to buy rowhammer-resistent RAM? I don't know, ask manufacturers and resellers I suppose? I don't make the spec sheets.

sroussey 4y ago
If you run a server farm, you absolutely know these things. And you are using ECC based RAM.
- mort96 4y ago
  Most of us don't run server farms.
  - sroussey 4y ago
    Most of us don’t care about rowhammer then either.
_3u10 4y ago
You have the option, you just choose not to pay for ECC ram.

suavesito 4y ago

That is fundamentally different. Floating point computation not nearly as always needs to be done to the last digit of precision. For a lot of application 10^-8 is more than enough, for some even less digits might be enough. But fast calculation might be a lot more important if you're in a real time scenario or if you're doing HPC. On the other hand, is not only row hammer attacks that cause bit flips, random bit flips happens, cosmic ray or decline of radioactive particles might cause one. And there is _no way_ to know if one happened on non ECC RAM (I know, ECC only reduces the probability of not noticing it, but it reduces that probability), and given that there is not way to respond. If one random bit flip happens, best case nothing happens. If you are unlucky, maybe your system will crash. If you are really unlucky your data might end up corrupted and the OS might not even be able to detect it. Or maybe you were running a 100 hours calculation, and it might go wrong in the first minutes because of a bit flip and your simulation is ruined. Floating point operations is about precision, witch can be studied and decided based on the needs of the application, bit flips are about data corruption.

_3u10 4y ago
I'm guessing more crashes occur because of bugs in software or RAM / CPUs that are already damaged than row hammering.