EIP-150: Gas cost changes for IO-heavy operations Source

Author Vitalik Buterin Final Standards Track Core 2016-09-24

Parameters

FORK_BLKNUM CHAIN_ID CHAIN_NAME
2,463,000 1 Main net

Specification

If block.number >= FORK_BLKNUM, then:

• Increase the gas cost of EXTCODESIZE to 700 (from 20).
• Increase the base gas cost of EXTCODECOPY to 700 (from 20).
• Increase the gas cost of BALANCE to 400 (from 20).
• Increase the gas cost of SLOAD to 200 (from 50).
• Increase the gas cost of CALL, DELEGATECALL, CALLCODE to 700 (from 40).
• Increase the gas cost of SELFDESTRUCT to 5000 (from 0).
• If SELFDESTRUCT hits a newly created account, it triggers an additional gas cost of 25000 (similar to CALLs).
• Increase the recommended gas limit target to 5.5 million.
• Define “all but one 64th” of N as N - floor(N / 64).
• If a call asks for more gas than the maximum allowed amount (i.e. the total amount of gas remaining in the parent after subtracting the gas cost of the call and memory expansion), do not return an OOG error; instead, if a call asks for more gas than all but one 64th of the maximum allowed amount, call with all but one 64th of the maximum allowed amount of gas (this is equivalent to a version of EIP-901 plus EIP-1142). CREATE only provides all but one 64th of the parent gas to the child call.

That is, substitute:

extra_gas = (not ext.account_exists(to)) * opcodes.GCALLNEWACCOUNT + \
(value > 0) * opcodes.GCALLVALUETRANSFER
if compustate.gas < gas + extra_gas:
return vm_exception('OUT OF GAS', needed=gas+extra_gas)
submsg_gas = gas + opcodes.GSTIPEND * (value > 0)

With:

def max_call_gas(gas):
return gas - (gas // 64)

extra_gas = (not ext.account_exists(to)) * opcodes.GCALLNEWACCOUNT + \
(value > 0) * opcodes.GCALLVALUETRANSFER
if compustate.gas < extra_gas:
return vm_exception('OUT OF GAS', needed=extra_gas)
if compustate.gas < gas + extra_gas:
gas = min(gas, max_call_gas(compustate.gas - extra_gas))
submsg_gas = gas + opcodes.GSTIPEND * (value > 0)

Rationale

This EIP aims to be simple, and adds a flat penalty of 300 gas on top of the costs calculated in this table to account for the cost of loading the code (~17–21 kb in the worst case).

The EIP 90 gas mechanic is introduced because without it, all current contracts that make calls would stop working as they use an expression like msg.gas - 40 to determine how much gas to make a call with, relying on the gas cost of calls being 40. Additionally, EIP 114 is introduced because, given that we are making the cost of a call higher and less predictable, we have an opportunity to do it at no extra cost to currently available guarantees, and so we also achieve the benefit of replacing the call stack depth limit with a “softer” gas-based restriction, thereby eliminating call stack depth attacks as a class of attack that contract developers have to worry about and hence increasing contract programming safety. Note that with the given parameters, the de-facto maximum call stack depth is limited to ~340 (down from ~1024), mitigating the harm caused by any further potential quadratic-complexity DoS attacks that rely on calls.

The gas limit increase is recommended so as to preserve the de-facto transactions-per-second processing capability of the system for average contracts.

1. EIP-90, https://github.com/ethereum/EIPs/issues/90
2. EIP-114, https://github.com/ethereum/EIPs/issues/114