Computation Cost

Since Klaytn aims to maintain 1-second block time, the execution time of transactions has to be managed. Here are three approaches to achieve that:

1. Limiting the gas limit of a transaction

2. Limiting the execution time of a transaction

3. Limiting the computation cost of a transaction

Limiting the gas limit of a transaction was not a feasible solution because the concept of the gas represents the current exchange value of the various resources in the blockchain platform such as computation, storage, network bandwidth, and so on. It is not suitable as a metric for the transaction execution time.

Limiting the execution time of a transaction was not feasible either because the execution time can vary between nodes on the blockchain platform. For example, consider the case in which we limit the execution time of a transaction to be 100 milli-second. If a node executes a transaction in 90 ms and another node executes it in 110 ms, the two nodes cannot reach a consensus. Hence, this solution is not appropriate.

The last approach is to limit the computation cost of a transaction. We modelled the computation cost of each EVM opcode based on its actual execution time and limit the sum of computation cost of a transaction. With this approach, we eliminate other factors and only count the normalized execution time unit, and nodes can reach a consensus as well.

Therefore, we chose the third option for Klaytn. For now, the limit of the execution cost is set to 100,000,000. Since the limit is determined by the platform, developers should be aware of the computation cost of a transaction. To calculate the computation cost of a transaction, Klaytn provides klay_estimateComputationCost. The usage is almost the same as klay_estimateGas.

Computation Cost of Opcodes

The below table shows the computation cost of EVM opcodes. The computation cost was determined based on experiments.

NOTE: Computation costs have changed with the Kore hardfork. If you want the previous document, please refer to previous document.

Kore hardfork block numbers are as follows.

• Baobab Testnet: #111736800

• Cypress Mainnet: #119750400

Opcode	ComputationCost
STOP	0
ADD	150
MUL	200
SUB	219
DIV	404
SDIV	739
MOD	812
SMOD	560
ADDMOD	1410
MULMOD	1760
EXP	5000
SIGNEXTEND	481
LT	201
GT	264
SLT	176
SGT	222
EQ	220
ISZERO	165
AND	288
OR	160
XOR	454
NOT	364
BYTE	589
SHL	478
SHR	498
SAR	834
SHA3	2465
ADDRESS	284
BALANCE	1407
ORIGIN	210
CALLER	188
CALLVALUE	149
CALLDATALOAD	596
CALLDATASIZE	194
CALLDATACOPY	100
CODESIZE	145
CODECOPY	898
GASPRICE	131
EXTCODESIZE	1481
EXTCODECOPY	1000
RETURNDATASIZE	10
RETURNDATACOPY	40
EXTCODEHASH	1000
BLOCKHASH	500
COINBASE	189
TIMESTAMP	265
NUMBER	202
PREVRANDAO	1498
GASLIMIT	166
CHAINID	120
SELFBALANCE	374
POP	140
MLOAD	376
MSTORE	288
MSTORE8	5142
SLOAD	835
SSTORE	1548
JUMP	253
JUMPI	176
PC	147
MSIZE	137
GAS	230
JUMPDEST	10
PUSH0	80
PUSH1	120
PUSH2	120
PUSH3	120
PUSH4	120
PUSH5	120
PUSH6	120
PUSH7	120
PUSH8	120
PUSH9	120
PUSH10	120
PUSH11	120
PUSH12	120
PUSH13	120
PUSH14	120
PUSH15	120
PUSH16	120
PUSH17	120
PUSH18	120
PUSH19	120
PUSH20	120
PUSH21	120
PUSH22	120
PUSH23	120
PUSH24	120
PUSH25	120
PUSH26	120
PUSH27	120
PUSH28	120
PUSH29	120
PUSH30	120
PUSH31	120
PUSH32	120
DUP1	190
DUP2	190
DUP3	176
DUP4	142
DUP5	177
DUP6	165
DUP7	147
DUP8	157
DUP9	138
DUP10	174
DUP11	141
DUP12	144
DUP13	157
DUP14	143
DUP15	237
DUP16	149
SWAP1	141
SWAP2	156
SWAP3	145
SWAP4	135
SWAP5	115
SWAP6	146
SWAP7	199
SWAP8	130
SWAP9	160
SWAP10	134
SWAP11	147
SWAP12	128
SWAP13	121
SWAP14	114
SWAP15	197
SWAP16	128
LOG0	100
LOG1	1000
LOG2	1000
LOG3	1000
LOG4	1000
PUSH	0
DUP	0
SWAP	0
CREATE	2094
CALL	5000
CALLCODE	4000
RETURN	0
DELEGATECALL	696
CREATE2	10000
STATICCALL	10000
REVERT	0
SELFDESTRUCT	0
BASEFEE	198