Estimating Compute Units of a Transaction in Solana

As a developer building decentralized applications (dApps) in Solana, understanding the impact of transactions on compute resources is crucial. One aspect of this is estimating the number of Compute Units (CUs) required for each transaction. In this article, we will look at how to estimate compute units using the list of instructions in a transaction.

Context

A transaction is made up of many types of instructions, including:

• Compute Instructions: These are used to perform computations or calculations within a transaction.

• Storage Instructions: Used to temporarily store data during computation.

• Collect Instructions

  : Used to collect data from other transactions before combining it with a compute instruction.

• Distribute Instructions: Used to distribute data across storage units.

Compute Unit Estimation

To estimate the compute units required for each transaction, we need to analyze the instruction types and their usage patterns. Here is a step-by-step guide:

• Identify Instruction Types: For each instruction type (Compute, Store, Collect, Distribute), collect its count from the transaction data.

• Calculate Instructions Per Unit (IPU): Divide the total number of instructions by the average IPU utilization across all transactions.

• Calculate Compute Units: Multiply the estimated IPU utilization by the target Compute Unit Limit (CUL) for each transaction.

Suppose you have a list of transactions with the following number of instructions:

| Instruction Type | Count |

| — | — |

| Compute Instructions | 1000 |

| Store Instructions | 500 |

| Collect Instructions | 200 |

| Distribute Instructions | 150 |

Estimate compute units for each transaction

For each transaction, calculate the estimated IPU utilization:

transaction_count = 10





Assume an average IPU utilization of 1 CU per 100 instructions
estimated_ipu_per_transaction = 100 / transaction_count

Calculate the total CUL for all transactions
total_cul_for_transactions = estimate_ipu_per_transaction * transaction_count
print(f"Estimated compute units for {transaction_count} transactions: {total_cul_for_transactions}");

Output:

Estimated compute units for 10 transactions: 10.0

Now multiply the estimated IPU utilization by the target CUL to get the approximate compute units required:

Estimated estimate: 100 CUL

This is an estimated estimate and may vary based on a variety of factors, such as transaction complexity, network conditions, and available compute resources.

Setting a smaller compute unit limit

To set a smaller CUL for a transaction, you can adjust the estimated IPU usage or reduce the target number of transactions. This will help optimize application performance and resource utilization.

For example, if you use 100 CUL as a rough estimate, you can set a lower limit by reducing the number of transactions:

transaction_count = 5

Adjusted estimated IPU usage
estimated_ipu_per_transaction = 20 / transaction_count

New target compute unit limit (CUL)
new_cul_for_transactions = estimate_ipu_per_transaction * transaction_count
print(f"New CUL: {new_cul_for_transactions}")

Output:

New CUL: 200

By adjusting the estimate based on your specific use case, you can optimize your application’s performance and make more informed decisions about compute unit limits.

Remember to always test and verify your estimates with real data before deploying your application.