7 ms·

Video games can scale just fine with many cores, including MMOs and games like Minecraft. Veloren, for example, uses multiple cores everywhere for just about e

Video games can scale just fine with many cores, including MMOs and games like Minecraft. Veloren, for example, uses multiple cores everywhere for just about everything--most of the gameplay loop, physics, chunk meshing, world generation, realtime simulation, rendering (can be parallelized a lot further now that we've switched to wgpu), networking, and background tasks like snapshotting persistence--and it is certainly not hard to find places where parallelization yields real speedup (quite the opposite--every time we further parallelize physics it yields significant performance improvements!). There are many hard problems in video game performance, but "games just can't make good use of multiple cores" is not one of them. If anything, I often wish we could rely on many more cores being available than actually are! It is certainly far far easier to see real performance wins with multicore than by using multiple servers, which introduce very heavy coordination costs.

forrestthewoods 5y ago
> There are many hard problems in video game performance, but "games just can't make good use of multiple cores" is not one of them. That's not quite what I said. I'm happy you're using specs to work on an open source game. Specs and bevy and all the ECS work being done is super exciting and fun. I <3 Rust. In the meantime there are no major games that effectively scale to, let's say, 64 cores. I don't know of anything shipped that can saturate a 12-core/24-thread Ryzen. ECS alone will not get us to that level of scaling. Yes it's trivial to to throw audio, networking, and a few other subsystems onto separate threads. Modern games definitely leverage 4 cores. Although several of those cores will be severely under utilized. Modern ECS designs are rapidly evolving and rapidly improving our ability to better leverage multiple cores. But we're not yet to a point where games can easily and efficiently saturate 10+ cores. Personally I'd love to see a game like Eve Online that can effectively simulate a universe with tens of thousands of players either spread across the universe or all in one places during one giant battle. > It is certainly far far easier to see real performance wins with multicore than by using multiple servers, which introduce very heavy coordination costs. This is extremely true.
- Jweb_Guru 5y ago
  If you're just using ECS to parallelize disjoint subsystems then no, it won't get you there. But if you're using it (as Veloren is, and as I hope more people do) in a more deliberate way, to further parallelize within a system, you can indeed scale quite well to large numbers of cores. I've done some theoretical bottleneck calculations and we will still have tons of work to do with 64 cores available, if the game is written properly. We can already get decent utilization out of 32 threads at busy times, and the server was not really close to peak load in terms of player count (and we are very far from done optimizing): https://media.discordapp.net/attachments/539518074106413056/825375910969737287/unknown.png https://media.discordapp.net/attachments/539518074106413056/.... That's just for our server. Our clients can make use of cores in even more ways, although they have less work to do and generally have fewer cores available, and you can see Veloren taking advantage of 16 client threads with similar utilization here: https://twitter.com/sahajsarup/status/1431837669391142916 https://twitter.com/sahajsarup/status/1431837669391142916. The most important thing I want to note is that in both cases, you are not seeing tremendous imbalance between the cores most of the time. While there are definitely single-threaded bottlenecks in games, you have to be working pretty hard before they start bottlenecking the workload! Instead, we are just suffering from a combination of general inefficiency and lack of work to do. So no, I'm going to push back against this notion that multicore scaling for games is some sort of crazy intractable problem. It's not. Like any other kind of parallel scaling, it's trivial in some places, more challenging in others, and depends a lot on your workload (including you actually having enough work to saturate the cores in the first place!). But there's nothing special about games here.
  - forrestthewoods 5y ago
    The original question was: > Is there a specific reason why Minecraft hasn’t been “adapted” from the original game to a robust design that could scale to larger worlds and player populations before your project ? The answer is because it's a lot of hard work. I am happy that a bunch of smart and talented people are working really hard to optimize Veloren. Good for you. I hope you help push the state of the art.

forrestthewoods 5y ago

> There are many hard problems in video game performance, but "games just can't make good use of multiple cores" is not one of them. That's not quite what I said. I'm happy you're using specs to work on an open source game. Specs and bevy and all the ECS work being done is super exciting and fun. I <3 Rust. In the meantime there are no major games that effectively scale to, let's say, 64 cores. I don't know of anything shipped that can saturate a 12-core/24-thread Ryzen. ECS alone will not get us to that level of scaling. Yes it's trivial to to throw audio, networking, and a few other subsystems onto separate threads. Modern games definitely leverage 4 cores. Although several of those cores will be severely under utilized. Modern ECS designs are rapidly evolving and rapidly improving our ability to better leverage multiple cores. But we're not yet to a point where games can easily and efficiently saturate 10+ cores. Personally I'd love to see a game like Eve Online that can effectively simulate a universe with tens of thousands of players either spread across the universe or all in one places during one giant battle. > It is certainly far far easier to see real performance wins with multicore than by using multiple servers, which introduce very heavy coordination costs. This is extremely true.

Jweb_Guru 5y ago
If you're just using ECS to parallelize disjoint subsystems then no, it won't get you there. But if you're using it (as Veloren is, and as I hope more people do) in a more deliberate way, to further parallelize within a system, you can indeed scale quite well to large numbers of cores. I've done some theoretical bottleneck calculations and we will still have tons of work to do with 64 cores available, if the game is written properly. We can already get decent utilization out of 32 threads at busy times, and the server was not really close to peak load in terms of player count (and we are very far from done optimizing): https://media.discordapp.net/attachments/539518074106413056/825375910969737287/unknown.png https://media.discordapp.net/attachments/539518074106413056/.... That's just for our server. Our clients can make use of cores in even more ways, although they have less work to do and generally have fewer cores available, and you can see Veloren taking advantage of 16 client threads with similar utilization here: https://twitter.com/sahajsarup/status/1431837669391142916 https://twitter.com/sahajsarup/status/1431837669391142916. The most important thing I want to note is that in both cases, you are not seeing tremendous imbalance between the cores most of the time. While there are definitely single-threaded bottlenecks in games, you have to be working pretty hard before they start bottlenecking the workload! Instead, we are just suffering from a combination of general inefficiency and lack of work to do. So no, I'm going to push back against this notion that multicore scaling for games is some sort of crazy intractable problem. It's not. Like any other kind of parallel scaling, it's trivial in some places, more challenging in others, and depends a lot on your workload (including you actually having enough work to saturate the cores in the first place!). But there's nothing special about games here.
- forrestthewoods 5y ago
  The original question was: > Is there a specific reason why Minecraft hasn’t been “adapted” from the original game to a robust design that could scale to larger worlds and player populations before your project ? The answer is because it's a lot of hard work. I am happy that a bunch of smart and talented people are working really hard to optimize Veloren. Good for you. I hope you help push the state of the art.