b0b606dabe
## Issue Addressed NA ## Proposed Changes I've noticed that our block hashing times increase significantly after the merge. I did some flamegraph-ing and noticed that we're allocating a `Vec` for each byte of each execution payload transaction. This seems like unnecessary work and a bit of a fragmentation risk. This PR switches to `SmallVec<[u8; 32]>` for the packed encoding of `TreeHash`. I believe this is a nice simple optimisation with no downside. ### Benchmarking These numbers were computed using #3580 on my desktop (i7 hex-core). You can see a bit of noise in the numbers, that's probably just my computer doing other things. Generally I found this change takes the time from 10-11ms to 8-9ms. I can also see all the allocations disappear from flamegraph. This is the block being benchmarked: https://beaconcha.in/slot/4704236 #### Before ``` [2022-09-15T21:44:19Z INFO lcli::block_root] Run 980: 10.553003ms [2022-09-15T21:44:19Z INFO lcli::block_root] Run 981: 10.563737ms [2022-09-15T21:44:19Z INFO lcli::block_root] Run 982: 10.646352ms [2022-09-15T21:44:19Z INFO lcli::block_root] Run 983: 10.628532ms [2022-09-15T21:44:19Z INFO lcli::block_root] Run 984: 10.552112ms [2022-09-15T21:44:19Z INFO lcli::block_root] Run 985: 10.587778ms [2022-09-15T21:44:19Z INFO lcli::block_root] Run 986: 10.640526ms [2022-09-15T21:44:19Z INFO lcli::block_root] Run 987: 10.587243ms [2022-09-15T21:44:19Z INFO lcli::block_root] Run 988: 10.554748ms [2022-09-15T21:44:19Z INFO lcli::block_root] Run 989: 10.551111ms [2022-09-15T21:44:19Z INFO lcli::block_root] Run 990: 11.559031ms [2022-09-15T21:44:19Z INFO lcli::block_root] Run 991: 11.944827ms [2022-09-15T21:44:19Z INFO lcli::block_root] Run 992: 10.554308ms [2022-09-15T21:44:19Z INFO lcli::block_root] Run 993: 11.043397ms [2022-09-15T21:44:19Z INFO lcli::block_root] Run 994: 11.043315ms [2022-09-15T21:44:19Z INFO lcli::block_root] Run 995: 11.207711ms [2022-09-15T21:44:19Z INFO lcli::block_root] Run 996: 11.056246ms [2022-09-15T21:44:19Z INFO lcli::block_root] Run 997: 11.049706ms [2022-09-15T21:44:19Z INFO lcli::block_root] Run 998: 11.432449ms [2022-09-15T21:44:19Z INFO lcli::block_root] Run 999: 11.149617ms ``` #### After ``` [2022-09-15T21:41:49Z INFO lcli::block_root] Run 980: 14.011653ms [2022-09-15T21:41:49Z INFO lcli::block_root] Run 981: 8.925314ms [2022-09-15T21:41:49Z INFO lcli::block_root] Run 982: 8.849563ms [2022-09-15T21:41:49Z INFO lcli::block_root] Run 983: 8.893689ms [2022-09-15T21:41:49Z INFO lcli::block_root] Run 984: 8.902964ms [2022-09-15T21:41:49Z INFO lcli::block_root] Run 985: 8.942067ms [2022-09-15T21:41:49Z INFO lcli::block_root] Run 986: 8.907088ms [2022-09-15T21:41:49Z INFO lcli::block_root] Run 987: 9.346101ms [2022-09-15T21:41:49Z INFO lcli::block_root] Run 988: 8.96142ms [2022-09-15T21:41:49Z INFO lcli::block_root] Run 989: 9.366437ms [2022-09-15T21:41:49Z INFO lcli::block_root] Run 990: 9.809334ms [2022-09-15T21:41:49Z INFO lcli::block_root] Run 991: 9.541561ms [2022-09-15T21:41:49Z INFO lcli::block_root] Run 992: 11.143518ms [2022-09-15T21:41:49Z INFO lcli::block_root] Run 993: 10.821181ms [2022-09-15T21:41:49Z INFO lcli::block_root] Run 994: 9.855973ms [2022-09-15T21:41:49Z INFO lcli::block_root] Run 995: 10.941006ms [2022-09-15T21:41:49Z INFO lcli::block_root] Run 996: 9.596155ms [2022-09-15T21:41:49Z INFO lcli::block_root] Run 997: 9.121739ms [2022-09-15T21:41:49Z INFO lcli::block_root] Run 998: 9.090019ms [2022-09-15T21:41:49Z INFO lcli::block_root] Run 999: 9.071885ms ``` ## Additional Info Please provide any additional information. For example, future considerations or information useful for reviewers. |
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