SIMD-0286: Increase block limits to 100M (#286)

* Add SIMD-0286 to increaes block limits to 100M

* lint

* pr feedback

Author: buffalu

proposals/0286-raise-block-limits-to-100M.md

@@ -0,0 +1,89 @@
+---
+simd: '0286'
+title: Increase Block Limits to 100M CUs
+authors:
+  - Lucas Bruder (Jito Labs)
+category: Standard
+type: Core
+status: Review
+created: 2025-05-20
+feature: TBD
+development:
+  - Anza - TBD
+  - Firedancer - TBD
+  - Jito Labs - TBD
+---
+
+## Summary
+
+Increase the block limit to 100M CUs.
+
+## Motivation
+
+Current block limits are set to 50M CUs. SIMD-0256 will increase them to 60M.
+Block limits' primary purpose is to ensure the vast majority of network
+participants are able to keep up with the network, by restricting the amount of
+work a leader is allowed to pack into a block. However, current mainnet traffic
+is largely not constrained by large block execution times. This proposal aims a
+substantial increase in block limits to 100M CUs, in order to provide additional
+capacity to the network.
+
+## New Terminology
+
+No new terms, but the following definitions are given for clarity:
+
+- Max Block Units - The maximum number of CUs that can be included in a block.
+- Max Writable Account Units - The maximum number of CUs that can be used to
+  write any given account in a block.
+- Max Vote Units - The maximum number of CUs that can be used by simple votes
+  in a block.
+- Max Block Accounts Data Size Delta - The maximum size of the accounts data
+  size delta in a block.
+
+## Detailed Design
+
+The following table shows the current block limits and the proposed block
+limits:
+
+| Type | Current Block Limit | SIMD-0256 Limit | Proposed Block Limit |
+|------|-----|-----------------|---------------------|
+| Max Block Units | 50M | 60M             | 100M |
+| Max Writable Account Units | 12M | 12M             | 12M |
+| Max Vote Units | 36M | 36M             | 36M  |
+| Max Block Accounts Data Size Delta | 100MB | 100MB           | 100MB |
+
+This proposal only changes the `Max Block Units` limit.
+The purpose is to increase capacity for non-vote transactions.
+The `Max Writable Account Units` is left unchanged since there is no specific
+push to increase the capacity for individual accounts at this time.
+Keeping `Max Writeable Account Units` unchanged while raising the
+`Max Block Units` , allows for additional parallel capacity.
+
+The intention is for this to follow SIMD-0256 (as opposed to replacing).
+SIMD-0256 is a much more modest increase in block space. This proposal 
+aims to increase block space more aggressively.
+
+## Alternatives Considered
+
+- Smaller increase of limit to 80M CUs
+    - Not IBRL'ing fast enough
+
+## Impact
+
+- More transactions can be included per block.
+
+## Security Considerations
+
+- Blocks may take longer to execute, slowing down network progress and catchup times.
+
+## Drawbacks
+
+- Larger blocks may cause unforseen issues in infrastructure beyond the
+  validators.
+
+## Backwards Compatibility
+
+- All previously valid blocks are still valid, since limits are only
+  increasing.
+- Blocks produced after the change may be rejected by previous versions that do
+  not support the new limits.