I think their usecase makes a lot of sense as their workloads consume a predefined amount of ram. As a customer you rent a VM with a specified amount of memory so fly.io does not care about reclaiming it from a running VM.
Depends on if they're using smart memory allocation to keep costs lower, IE, if they can pattern that certain workloads only need N amount of memory at Y time, they can effectively borrow memory from one VM for usage in another that has an opposite statistical likelihood of needing that memory.
This is why paying for dedicated memory is often more expensive than its counter part, because that dedicated memory is not considered as part of pooling.
Generalized oversubscription like that is very challenging if not impossible to do securely, since you want to keep workloads isolated to single tenant numa nodes.
I think it would be easier to just enable KSM (KVM can use it to deduplicate memory and save some RAM on duplicate blocks like people loading same libraries into memory)
I think their usecase makes a lot of sense as their workloads consume a predefined amount of ram. As a customer you rent a VM with a specified amount of memory so fly.io does not care about reclaiming it from a running VM.
Depends on if they're using smart memory allocation to keep costs lower, IE, if they can pattern that certain workloads only need N amount of memory at Y time, they can effectively borrow memory from one VM for usage in another that has an opposite statistical likelihood of needing that memory.
This is why paying for dedicated memory is often more expensive than its counter part, because that dedicated memory is not considered as part of pooling.
Generalized oversubscription like that is very challenging if not impossible to do securely, since you want to keep workloads isolated to single tenant numa nodes.
E.g. using the firecracker jailer: https://github.com/firecracker-microvm/firecracker/blob/main...
I think it would be easier to just enable KSM (KVM can use it to deduplicate memory and save some RAM on duplicate blocks like people loading same libraries into memory)
Shit like this is how you burn customers and then they find out you aren't changing the sheets, they change hotels.
Just because you can doesn't mean you should.
13 replies →
We like Firecracker. People should use whatever makes sense for them.