EIP 4844 - Multidimensional fee

EIP 4844 - Multidimensional fee

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3 min read

Today let us read about the changes that EIP4844 will bring to the gas fee paid by the users. So, by now we have the basic understanding of Proto-Danksharding. If not, you can read it here.

With the addition of blobs to the transaction, a new parameter has been added to the EIP fee structure and thus it is known as MULTI-DIMENSIONAL fee.

The new fee structure contains 6 parameters for the gas with 3 parameters for each resource.

That is, there are two variables and four constants:

Target per block

Max per block

Base Fee

Gas

15 million

30 million

Variable

Blob

8

16

Variable

The blob fee is also paid in gas and it is a variable and it gets adjusted in the long run to support the higher number of blobs per block and eventually reach the target count.

With the two dimensional fee structure, it is gonna be a harder problem for the block producer. Traditionally, the block producers can simply accept the transaction with highest priority fee (in EIP - 1559) to mine until they run out of the transactions in the mempool or reach the block gas limit. But now, they have to pick transactions which pay more fee and have to simultaneously avoid hitting the limits of both gas limit and blob gas limit.

Here’s an example. Suppose that the gas limit is 70 and the blob limit is 40. The mempool has many transactions, enough to fill the block, of two types (tx gas includes the per-blob gas):

  • Priority fee 5 per gas, 4 blobs, 4 total gas

  • Priority fee 3 per gas, 1 blob, 2 total gas

A miner that follows the naive “walk down the priority fee” algorithm would fill the entire block with 10 transactions (40 gas) of the first type, and get a revenue of 5 40 = 200. Because these 10 transactions fill up the blob limit completely, they would not be able to include any more transactions. But the optimal strategy is to take 3 transactions of the first type and 28 of the second type. This gives you a block with 40 blobs and 68 gas, and 5 12 + 3 * 56 = 228 revenue.

Let us look into a transaction to analyze this.

https://etherscan.io/tx/0xa3e36193ab5ca4e6e98848640b1896def4c419ce203e7bd8e876dd2d5eb77e6c

The gas price structure is similar to the regular EIP1559 transaction. But if we move into the BLOB section of the transaction, then we can check the details of the blob gas fee and other details.

Here we can see the details of the blob gas such as blob gas used and blob gas price. And also for they have provided the gas price of the transaction if the blob data is sent as a calldata in a regular transaction. And we can see that makes the transaction almost 16 times more expensive.