Merge pull request #2034 from ethereum/vbuterin-patch-5

Add a constant for slash penalty multiplier

configs/mainnet/phase0.yaml

@@ -27,6 +27,8 @@ HYSTERESIS_QUOTIENT: 4
 HYSTERESIS_DOWNWARD_MULTIPLIER: 1
 # 5 (plus 1.25)
 HYSTERESIS_UPWARD_MULTIPLIER: 5
+# 3
+PROPORTIONAL_SLASHING_MULTIPLIER: 3
 
 
 # Fork Choice

configs/minimal/phase0.yaml

@@ -26,7 +26,8 @@ HYSTERESIS_QUOTIENT: 4
 HYSTERESIS_DOWNWARD_MULTIPLIER: 1
 # 5 (plus 1.25)
 HYSTERESIS_UPWARD_MULTIPLIER: 5
-
+# 3
+PROPORTIONAL_SLASHING_MULTIPLIER: 3
 
 
 # Fork Choice

specs/phase0/beacon-chain.md

@@ -195,6 +195,7 @@ The following values are (non-configurable) constants used throughout the specif
 | `HYSTERESIS_QUOTIENT` | `uint64(4)` |
 | `HYSTERESIS_DOWNWARD_MULTIPLIER` | `uint64(1)` |
 | `HYSTERESIS_UPWARD_MULTIPLIER` | `uint64(5)` |
+| `PROPORTIONAL_SLASHING_MULTIPLIER` | `uint64(3)` |
 
 - For the safety of committees, `TARGET_COMMITTEE_SIZE` exceeds [the recommended minimum committee size of 111](http://web.archive.org/web/20190504131341/https://vitalik.ca/files/Ithaca201807_Sharding.pdf); with sufficient active validators (at least `SLOTS_PER_EPOCH * TARGET_COMMITTEE_SIZE`), the shuffling algorithm ensures committee sizes of at least `TARGET_COMMITTEE_SIZE`. (Unbiasable randomness with a Verifiable Delay Function (VDF) will improve committee robustness and lower the safe minimum committee size.)
 
@@ -1554,10 +1555,11 @@ def process_registry_updates(state: BeaconState) -> None:
 def process_slashings(state: BeaconState) -> None:
     epoch = get_current_epoch(state)
     total_balance = get_total_active_balance(state)
+    adjusted_total_slashing_balance = min(sum(state.slashings) * PROPORTIONAL_SLASHING_MULTIPLIER, total_balance)
     for index, validator in enumerate(state.validators):
         if validator.slashed and epoch + EPOCHS_PER_SLASHINGS_VECTOR // 2 == validator.withdrawable_epoch:
             increment = EFFECTIVE_BALANCE_INCREMENT  # Factored out from penalty numerator to avoid uint64 overflow
-            penalty_numerator = validator.effective_balance // increment * min(sum(state.slashings) * 3, total_balance)
+            penalty_numerator = validator.effective_balance // increment * adjusted_total_slashing_balance
             penalty = penalty_numerator // total_balance * increment
             decrease_balance(state, ValidatorIndex(index), penalty)
 ```