Question regarding Gas Smashing Patterns in Sui Transfers

[ichiburn]

Question regarding Gas Smashing Patterns in Sui Transfers

Overview

While experimenting with Sui transfer transactions on DevNet, I observed consistent gas calculation patterns and "Gas smashing" messages. I'd like to understand if this is intended behavior and the reasoning behind it.

Observations

Test Scenarios

I tested three different transfer scenarios:

1. Large amount transfer (2 SUI):

sui client transfer-sui \
  --sui-coin-object-id 0x55d26b04e7553439b69f1eb512c2efe4064ef9b57671507289856ba435958754 \
  --amount 2000000000 \
  --to 0x8525647ea6b1e3505ea4796ba8b513d73db9d05db2724c14bcd2d4cb568112d7 \
  --gas-budget 10000000

2. Minimal amount transfer (100 MIST):

sui client transfer-sui \
  --amount 100 \
  [same parameters as above]

3. Medium amount with minimal gas budget (1 SUI, 3M MIST budget):

sui client transfer-sui \
  --amount 1000000 \
  --gas-budget 3000000
  [same parameters as above]

Interesting Patterns Observed

1. Consistent Gas Costs

   • All transactions show identical costs:

     Storage Cost: 1,976,000 MIST
     Computation Cost: 1,000,000 MIST
     Storage Rebate: 978,120 MIST
     Non-refundable Storage Fee: 9,880 MIST
     

2. Object Properties

   • All objects (new and modified) are 130 bytes
   • Consistent rebate pattern:
     • New objects: 0 → 988,000 MIST
     • Modified objects: 988,000 MIST → 988,000 MIST

3. Execution Metrics

   • Zero bytecode instructions reported
   • Maximum gas stack height: 0
   • Reference gas price: 1000 MIST

Questions

1. Design Intent

   • Is this consistent gas cost pattern intentional?
   • What's the purpose of "Gas smashing" in this context?

2. Technical Understanding

   • Why are bytecode instructions showing as 0?
   • Is the consistent object size (130 bytes) expected for all transfer transactions?
   • How is the storage rebate amount (988,000 MIST) determined?

3. Best Practices

   • Is this behavior documented somewhere in the Sui docs?
   • Are there specific considerations when implementing gas estimation in applications?
   • Should we expect this behavior to change in future versions?

Environment Details

• Network: Sui DevNet
• Sui CLI Version: v1.42.0
• Test Transaction Hashes:
  1. DMpgF9YvnGKkd9aT8ov7c6x73kzzJosdYaEtxWzj9tEB
  2. Dkke8R5sXwZLWAVWzmSDWB8RBBiaA9TJNeijBFgzrr9f
  3. 81C5VbUUCfDDvpewnDugcXqUr8DTDb8YtVbaHb7jz3js

Related Information

I noticed some related PRs (#8645, #7805, #11202) mentioning gas smashing, but I'd love to understand how they relate to this behavior.

Additional Context

• All transactions completed successfully
• Behavior is 100% reproducible
• No negative impact on transaction execution
• Consistent across different gas budgets

References

• Sui Documentation

I appreciate any insights into understanding this behavior better!