implement FIP-0032 gas parameters and charges #534

raulk · 2022-05-06T14:48:53Z

Fully implements filecoin-project/FIPs#368 in ref-fvm.

Also changes the unit in pricelists to milligas, and removes now unnecessary functions that dealt with full-unit gas charges.
Adds i64 Gas and Milligas type aliases for extra clarity (but not safety) in APIs.

Static parameters in pricelists were updated to use a non-saturating macro.

Runtime milligas conversions were needed here:

message prevalidation: needs to do milligas conversion when evaluating the inclusion cost.
charge_gas syscall handler: I placed it here instead of making Kernel#charge_gas accept full Gas for two reasons, to preserve unit homogeneity in charge_* operations throughout the codebase.

Note

Need to review all on_* price list formulae because some aren't using saturation arithmetics (inherited). I don't want to continue growing this patch, so we should follow up with this on master.

Closes #363.

Canonical unit is now milligas everywhere.

raulk · 2022-05-06T14:50:43Z

fvm/src/gas/price_list.rs

+        // Rules valid for nv16. We will need to be generic over Rules (massive
+        // generics tax), use &dyn Rules (which breaks other things), or pass
+        // in the network version, or rules version, to vary these prices going
+        // forward.


@Stebalien something to take into account.

In this case, we can likely do &'static dyn Rules. Or, if we can't statically allocate, Box<dyn Rules>.

fvm/src/gas/price_list.rs

Kubuxu · 2022-05-06T15:43:04Z

fvm/src/kernel/default.rs

+            .charge_gas(self.call_manager.price_list().on_extern())?;
+


Nit: This repeated pattern makes me think that we should have a capability to either charge for both charges at once or the capability to combine charges into one but it isn't something that needs to get done.

It also shouldn't be consensus critical if we want to add this capability in future.

Agree. I started hacking on a const generics version of charge_gas_n that took an array and applied all charges sequentially. A few months ago I had also proposed a closure-based version of charge_gas that took the price list as an argument. That would also remove some pedanticness. However, we can explore these APIs later; right now it doesn't hurt having two explicit charges.

raulk · 2022-05-07T17:03:57Z

I have no idea why clippy complains here about this and not on master :-/

magik6k

Mostly being nitpicky, this looks good.

magik6k · 2022-05-09T18:27:54Z

fvm/src/syscalls/mod.rs

+/// Applies gas charges upon passing control to the FVM via a syscall.
+/// It first applies accumulated execution gas, and then applies the syscall
+/// charge for the currently active syscall.
+pub fn apply_charges_on_syscall(


Being nitpicky here, but technically this is a charge on exiting wasm, not just syscalls.

This is actually a bug. We call this when we return from wasm as well.

Good catch, thanks for that!

Will fix this tomorrow.

fvm/src/gas/price_list.rs

Stebalien · 2022-05-09T19:12:05Z

fvm/src/gas/price_list.rs

+        // Rules valid for nv16. We will need to be generic over Rules (massive
+        // generics tax), use &dyn Rules (which breaks other things), or pass
+        // in the network version, or rules version, to vary these prices going
+        // forward.


In this case, we can likely do &'static dyn Rules. Or, if we can't statically allocate, Box<dyn Rules>.

fvm/src/kernel/default.rs

Stebalien · 2022-05-09T19:18:22Z

fvm/src/syscalls/mod.rs

+/// Applies gas charges upon passing control to the FVM via a syscall.
+/// It first applies accumulated execution gas, and then applies the syscall
+/// charge for the currently active syscall.
+pub fn apply_charges_on_syscall(


This is actually a bug. We call this when we return from wasm as well.

Stebalien · 2022-05-09T19:20:57Z

fvm/src/gas/price_list.rs

-        block_open_base: 114617,
-        block_read_base: 0,
+        block_open_base: static_milligas!(114617),
+        block_open_memret_per_byte_cost: 0,


What is memret?

The memory retention cost (see section under https://github.com/filecoin-project/FIPs/blob/master/FIPS/fip-0032.md#ipld-state-management-gas).

(Can rename to something else, if it sounds like memory return).

Kubuxu · 2022-05-09T19:29:51Z

fvm/src/gas/price_list.rs


-        on_chain_return_value_per_byte: 1,
+        on_chain_return_value_per_byte: static_milligas!(1),


Personally, I would set the *_per_byte storage costs to 1 instead of 1000.
They have an implicit unit of bytes, and then they get multiplied by storage_gas_multiplier would be milltigas/byte.

Hm, it's actually implemented the other way around now. The multiplier is no longer denominated in milligas, but as a unitless factor. Are you good with that?

Yeah, I’m fine with that

raulk added 8 commits May 5, 2022 17:32

exec gas: apply only on non-structural instructions.

b2757db

pricelist: add new gas fees.

7102ce7

gas: fully switch to milligas as canonical unit.

4933e51

price list: update gas cost formulae.

91bec8a

price list: vertical spacing.

771dbcc

kernel: apply extern gas.

8ffcedf

syscalls: charge for gas; small refactors.

7c0f9a9

remove Kernel#charge_milligas().

c98f046

Canonical unit is now milligas everywhere.

raulk commented May 6, 2022

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raulk added 2 commits May 7, 2022 16:32

fix tests.

eb7e7fc

fix param.

952f11a

raulk force-pushed the raulk/fip-0032-parameters branch from a846563 to 8da9820 Compare May 7, 2022 17:49

clippy.

6208be5

raulk force-pushed the raulk/fip-0032-parameters branch from 8da9820 to 6208be5 Compare May 7, 2022 17:58

raulk added 2 commits May 7, 2022 19:11

add comment.

9183750

fix gas instrumentation.

9999204

raulk force-pushed the raulk/fip-0032-parameters branch from 15f97c9 to 9999204 Compare May 7, 2022 18:29

raulk added 8 commits May 8, 2022 21:47

rename GasTracker#{charge_gas=>apply_charge} to disambiguate.

76f07a4

add Gas and Milligas unit types to disambiguate.

d19ef2e

convert public gas charges to milligas.

a798545

inclusion cost: adapt to milligas.

be0fdb1

charge_gas: move conversion to milligas to syscall handler.

4bb0a89

{to_milligas=>static_milligas}; make private.

17b1e0b

clippy.

b7b41d0

price list: remove compute_gas_multiplier (unused).

573afca

raulk added 3 commits May 9, 2022 12:26

polish comment.

2a957c1

use saturation arithmetics for mem costs.

c8b5241

Merge branch 'master' into raulk/fip-0032-parameters

1dd5c51

raulk marked this pull request as ready for review May 9, 2022 11:34

raulk requested review from Kubuxu, Stebalien, magik6k and arajasek May 9, 2022 11:36

magik6k approved these changes May 9, 2022

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Stebalien reviewed May 9, 2022

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Kubuxu reviewed May 9, 2022

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arajasek approved these changes May 9, 2022

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raulk added 3 commits May 9, 2022 23:32

price list: use Milligas type for cost fields.

4d0d8bd

rename Kernel#charge_{=>milli}gas.

5fe4437

add extern cost in syscall pricing formulae.

2bd6769

raulk force-pushed the raulk/fip-0032-parameters branch from 2bd8913 to 2bd6769 Compare May 9, 2022 23:08

charge for syscall gas at the right place.

5791726

raulk requested review from Kubuxu and Stebalien May 10, 2022 18:42

raulk added the hint/re-review label May 10, 2022

raulk merged commit 6a3dec1 into master May 10, 2022

raulk deleted the raulk/fip-0032-parameters branch May 10, 2022 18:50

raulk removed the hint/re-review label May 16, 2022

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implement FIP-0032 gas parameters and charges #534

implement FIP-0032 gas parameters and charges #534

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Kubuxu May 10, 2022


		on_chain_return_value_per_byte: 1,
		on_chain_return_value_per_byte: static_milligas!(1),

implement FIP-0032 gas parameters and charges #534

implement FIP-0032 gas parameters and charges #534

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