[SC-3392] Decide how expensive transactions should be

[dandanlen]

Description

Currently the multiplier to translate benchmark weights to fees is 1.

This means we value our block space/time at 6 * 1_000_000_000_000 flipperinos per block, or 6 micro-FLIP per block. Over a one-month epoch (~400k blocks) that amounts to a grand total of 2.4 FLIP. Validator rewards in the same period are projected to be around 450k FLIP (based on 6% inflation @ 90M initial supply).

I suggest we set or multiplier to between 1k and 10k: this way at most 0.5% - 5% of emissions will be eaten by fees.

(please dobule-check my maths).

Relevant people

@morelazers

[morelazers]

How easy is this multiplier to change? Could it ever be dynamic in future?

[dandanlen]

At the moment it's a constant but we can do whatever we want.

[morelazers]

10k seems fine.

The important thing in the long run is that there is some market for block space, though off the top of my head I think that this might only make sense for Relayer transactions. All Validator transactions as are important as one another (I think?) and should be prioritised for inclusion, whereas Relayers might have different ideas about the value of their swap intent vs someone else's; especially if we go down the route of giving a relayer some kickback based on volume.

[dandanlen]

Yes I don't think we want a market for validator transactions. But we do need some mechanism for prioritising validator txs over others. A fee market for relayers might be useful, yes but I think this is controller via another dial... here we're talking purely about the base multipliers: one for the size of the extrinsic (block space) and another for the weight (ie. execution cost).

Also it doesn't have to be a constant multiplier ie. it can be a non-linear function of the weight.

[dandanlen]

Just adding to this - another reason for sensible fees is spam-prevention of course.

I'll set the multiplier to 10k for the time being.