5 ms·

As a game dev, I agree with you. Also: all the casual observers that say "just multithread/core it! would make it so much faster!" and don't understand one bit

by rf15 8y ago

As a game dev, I agree with you. Also: all the casual observers that say "just multithread/core it! would make it so much faster!" and don't understand one bit about parallelisation problems, as if it's just a bit you flip.

garmaine 8y ago
To be fair of the criticism, game engines are way behind the stage of the art in concurrency and parallelism. It’s not as easy a flipping a switch, but it shouldn’t be as dire as it is either.
- cogman10 8y ago
  I think the big problem is that games are hyper optimized for single threaded performance. ECS systems are basically big arrays of mutable data manipulated by multiple systems. To do threading well, you'd pretty much have to dump that. Not to say they aren't behind. I once saw a game talk about how awesome they are because they reinvented a thread pool. But their state of the art is in direct conflict with good threading practices.
  - auto 8y ago
    Unfortunately, we haven't seen the paradigm shift in game engine development that would be necessary to really get away from hyper optimized single threaded performance. Until someone figures out a way to efficiently utilize (highly) parallel execution in a deterministic game engine that has to run at at least 60fps, there isn't an incentive to move beyond the tried and true ways of doing things. At least, I don't think we have, I'm not in AAA and only keep a tangential pulse on that level of gamedev. That said, I'd be really interested to see how some of these Battle Royale engines tick (no pun intended). It seems like there's a ton of potential for "clustering" execution, essentially treating separate sections of maps as separate games, but considering it could come down to 100 people all being within the same 100 square meters, you can't necessarily rely on that model.
    - vonmoltke 8y ago
      > Until someone figures out a way to efficiently utilize (highly) parallel execution in a deterministic game engine that has to run at at least 60fps, there isn't an incentive to move beyond the tried and true ways of doing things. I was doing that 10 years ago... in a radar signal processor. I could do the same thing in a game engine, but the games industry seems to be allergic to devs who do not come up in the games industry. I suspect that has as much to do with the poor state of parallelism as anything.
  - ethbro 8y ago
    They're optimized that way for a reason. It'll be a number of years yet for large-scale multithreading to penetrate the consumer market. 92% of users still have 2 or 4 physical CPUs, so 2-8 threads. https://store.steampowered.com/hwsurvey/Steam-Hardware-Software-Survey-Welcome-to-Steam https://store.steampowered.com/hwsurvey/Steam-Hardware-Softw...
    - lev99 8y ago
      There is a big difference between 2core/2thread and 4core/8thread. It would be interesting to see more granular data.
      - ethbro 8y ago
        Is the difference of physical cores vs modern SMT that big for gaming? I'd assume given asset size they're already dealing with a large amount of cache misses, and if you're stalling for a memory read anyway then it seems less impactful than on a high-thoroughput tuned scientific workload.
- lev99 8y ago
  Actually, I think game endings define the art of concurrency. GPUs have hundreds of threads, and the SIMD paradigm is more powerful than the more flexible MIMD one used by most multithreaded server frameworks.

by rf15 8y ago

garmaine 8y ago

To be fair of the criticism, game engines are way behind the stage of the art in concurrency and parallelism. It’s not as easy a flipping a switch, but it shouldn’t be as dire as it is either.

cogman10 8y ago
I think the big problem is that games are hyper optimized for single threaded performance. ECS systems are basically big arrays of mutable data manipulated by multiple systems. To do threading well, you'd pretty much have to dump that. Not to say they aren't behind. I once saw a game talk about how awesome they are because they reinvented a thread pool. But their state of the art is in direct conflict with good threading practices.
- auto 8y ago
  Unfortunately, we haven't seen the paradigm shift in game engine development that would be necessary to really get away from hyper optimized single threaded performance. Until someone figures out a way to efficiently utilize (highly) parallel execution in a deterministic game engine that has to run at at least 60fps, there isn't an incentive to move beyond the tried and true ways of doing things. At least, I don't think we have, I'm not in AAA and only keep a tangential pulse on that level of gamedev. That said, I'd be really interested to see how some of these Battle Royale engines tick (no pun intended). It seems like there's a ton of potential for "clustering" execution, essentially treating separate sections of maps as separate games, but considering it could come down to 100 people all being within the same 100 square meters, you can't necessarily rely on that model.
  - vonmoltke 8y ago
    > Until someone figures out a way to efficiently utilize (highly) parallel execution in a deterministic game engine that has to run at at least 60fps, there isn't an incentive to move beyond the tried and true ways of doing things. I was doing that 10 years ago... in a radar signal processor. I could do the same thing in a game engine, but the games industry seems to be allergic to devs who do not come up in the games industry. I suspect that has as much to do with the poor state of parallelism as anything.
- ethbro 8y ago
  They're optimized that way for a reason. It'll be a number of years yet for large-scale multithreading to penetrate the consumer market. 92% of users still have 2 or 4 physical CPUs, so 2-8 threads. https://store.steampowered.com/hwsurvey/Steam-Hardware-Software-Survey-Welcome-to-Steam https://store.steampowered.com/hwsurvey/Steam-Hardware-Softw...
  - lev99 8y ago
    There is a big difference between 2core/2thread and 4core/8thread. It would be interesting to see more granular data.
    - ethbro 8y ago
      Is the difference of physical cores vs modern SMT that big for gaming? I'd assume given asset size they're already dealing with a large amount of cache misses, and if you're stalling for a memory read anyway then it seems less impactful than on a high-thoroughput tuned scientific workload.
lev99 8y ago
Actually, I think game endings define the art of concurrency. GPUs have hundreds of threads, and the SIMD paradigm is more powerful than the more flexible MIMD one used by most multithreaded server frameworks.