Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

adjust hysteresis to avoid initial over-deposit incentive #1627

Merged
merged 3 commits into from
Mar 3, 2020
Merged

adjust hysteresis to avoid initial over-deposit incentive #1627

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
a02aac4
adjust hysteresis to avoid initial over-deposit incentive
djrtwo Feb 18, 2020
0122081
hysteresis to -0.25/+1.25
djrtwo Mar 2, 2020
33e7680
make hysteresis calculations configurable
djrtwo Mar 3, 2020
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
6 changes: 6 additions & 0 deletions configs/mainnet.yaml
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,12 @@ SHUFFLE_ROUND_COUNT: 90
MIN_GENESIS_ACTIVE_VALIDATOR_COUNT: 16384
# Jan 3, 2020
MIN_GENESIS_TIME: 1578009600
# 4
HYSTERESIS_QUOTIENT: 4
# 1 (minus 0.25)
HYSTERESIS_DOWNWARD_MULTIPLIER: 1
# 5 (plus 1.25)
HYSTERESIS_UPWARD_MULTIPLIER: 5
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

So previous behavior is, for context:

HYSTERESIS_QUOTIENT: 2
HYSTERESIS_DOWNWARD_MULTIPLIER: 0
HYSTERESIS_UPWARD_MULTIPLIER: 3



# Fork Choice
Expand Down
7 changes: 7 additions & 0 deletions configs/minimal.yaml
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,13 @@ SHUFFLE_ROUND_COUNT: 10
MIN_GENESIS_ACTIVE_VALIDATOR_COUNT: 64
# Jan 3, 2020
MIN_GENESIS_TIME: 1578009600
# 4
HYSTERESIS_QUOTIENT: 4
# 1 (minus 0.25)
HYSTERESIS_DOWNWARD_MULTIPLIER: 1
# 5 (plus 1.25)
HYSTERESIS_UPWARD_MULTIPLIER: 5



# Fork Choice
Expand Down
13 changes: 11 additions & 2 deletions specs/phase0/beacon-chain.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -183,6 +183,10 @@ The following values are (non-configurable) constants used throughout the specif
| `SHUFFLE_ROUND_COUNT` | `90` |
| `MIN_GENESIS_ACTIVE_VALIDATOR_COUNT` | `2**14` (= 16,384) |
| `MIN_GENESIS_TIME` | `1578009600` (Jan 3, 2020) |
| `HYSTERESIS_QUOTIENT` | `4` |
| `HYSTERESIS_DOWNWARD_MULTIPLIER` | `1` |
| `HYSTERESIS_UPWARD_MULTIPLIER` | `5` |


- 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.)

Expand Down Expand Up @@ -1402,8 +1406,13 @@ def process_final_updates(state: BeaconState) -> None:
# Update effective balances with hysteresis
for index, validator in enumerate(state.validators):
balance = state.balances[index]
HALF_INCREMENT = EFFECTIVE_BALANCE_INCREMENT // 2
if balance < validator.effective_balance or validator.effective_balance + 3 * HALF_INCREMENT < balance:
HYSTERESIS_INCREMENT = EFFECTIVE_BALANCE_INCREMENT // HYSTERESIS_QUOTIENT
DOWNWARD_THRESHOLD = HYSTERESIS_INCREMENT * HYSTERESIS_DOWNWARD_MULTIPLIER
UPWARD_THRESHOLD = HYSTERESIS_INCREMENT * HYSTERESIS_UPWARD_MULTIPLIER
if (
balance + DOWNWARD_THRESHOLD < validator.effective_balance
or validator.effective_balance + UPWARD_THRESHOLD < balance
):
validator.effective_balance = min(balance - balance % EFFECTIVE_BALANCE_INCREMENT, MAX_EFFECTIVE_BALANCE)
# Reset slashings
state.slashings[next_epoch % EPOCHS_PER_SLASHINGS_VECTOR] = Gwei(0)
Expand Down
22 changes: 14 additions & 8 deletions tests/core/pyspec/eth2spec/test/phase_0/epoch_processing/test_process_final_updates.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -51,19 +51,25 @@ def test_effective_balance_hysteresis(spec, state):
max = spec.MAX_EFFECTIVE_BALANCE
min = spec.EJECTION_BALANCE
inc = spec.EFFECTIVE_BALANCE_INCREMENT
half_inc = inc // 2
div = spec.HYSTERESIS_QUOTIENT
hys_inc = inc // div
down = spec.HYSTERESIS_DOWNWARD_MULTIPLIER
up = spec.HYSTERESIS_UPWARD_MULTIPLIER
cases = [
(max, max, max, "as-is"),
(max, max - 1, max - inc, "round down, step lower"),
(max, max - 1, max, "round up"),
(max, max + 1, max, "round down"),
(max, max - down * hys_inc, max, "lower balance, but not low enough"),
(max, max - down * hys_inc - 1, max - inc, "lower balance, step down"),
(max, max + (up * hys_inc) + 1, max, "already at max, as is"),
(max, max - inc, max - inc, "exactly 1 step lower"),
(max, max - inc - 1, max - (2 * inc), "just 1 over 1 step lower"),
(max, max - inc - 1, max - (2 * inc), "past 1 step lower, double step"),
(max, max - inc + 1, max - inc, "close to 1 step lower"),
(min, min + (half_inc * 3), min, "bigger balance, but not high enough"),
(min, min + (half_inc * 3) + 1, min + inc, "bigger balance, high enough, but small step"),
(min, min + (half_inc * 4) - 1, min + inc, "bigger balance, high enough, close to double step"),
(min, min + (half_inc * 4), min + (2 * inc), "exact two step balance increment"),
(min, min + (half_inc * 4) + 1, min + (2 * inc), "over two steps, round down"),
(min, min + (hys_inc * up), min, "bigger balance, but not high enough"),
(min, min + (hys_inc * up) + 1, min + inc, "bigger balance, high enough, but small step"),
(min, min + (hys_inc * div * 2) - 1, min + inc, "bigger balance, high enough, close to double step"),
(min, min + (hys_inc * div * 2), min + (2 * inc), "exact two step balance increment"),
(min, min + (hys_inc * div * 2) + 1, min + (2 * inc), "over two steps, round down"),
]
current_epoch = spec.get_current_epoch(state)
for i, (pre_eff, bal, _, _) in enumerate(cases):
Expand Down