Revisit fee for wasm msg size

[alpe]

With the new deserialization fee in wasmvm we charge twice

[webmaster128]

Could you elaborate what we charge twice and where?

wasmvm charges for the work done in wasmvm (the deserialization from the contract's binary response into Go structures). wasmd should charge for any work performed after that.

[alpe]

In the gas register we multiply the incoming message size by a factor see https://github.com/CosmWasm/wasmd/blob/master/x/wasm/keeper/gas_register.go#L127 .

[webmaster128]

But this is the input into the contract, not the output. So it does not duplicate the new deserialization fee in wasmvm.

However, the deserialization of input messages is executed in Wasm and metered there. So if there is no significant work in wasmd at this point, we can reconsider the linked fee.