CPU block effort - 1.8

[heifner]

Change Description

CPU block effort provides a mechanism to restrict the amount of time a producer is processing transactions for inclusion into a block. It also controls the time a producer will finalize/produce and transmit a block. Block construction now always begins at whole or half seconds for the next block.

Added new options cpu-effort-percent & last-block-cpu-effort-percent defaulted to 80%. Percentage of cpu block production time used to produce block. Whole number percentages, e.g. 80 for 80%.

These options allow time outside of start_block for other system activity such as net_plugin sending/receiving blocks, signing of block, etc.

Existing options produce-time-offset-us & last-block-time-offset-us have been modified to constrain configurable values from 0 .. -block_time_interval where currently block_time_interval is 500,000us. Positive values are no longer allowed.

The default value of produce-time-offset-us is now effectively -100000 since cpu-effort-percent is defaulted to 80%.

These four options now all fold into restricting the amount of time spent processing transactions into a block. The last-block-* options constrain the final 12th block of the producer's round. The other two options constrain the remaining blocks of the round, 1-11. The more constraining amount is used. For example, --cpu-effort-percent 80 --produce-time-offset-us -300000 will constrain transaction processing to 200ms as 80% x 500ms = 400ms and 500ms - 300ms = 200ms.

Other examples:
--cpu-effort-percent 70 --produce-time-offset-us -100000 provides 350ms for transaction processing.
--last-block-cpu-effort-percent 70 --last-block-time-offset-us -400000 provides 100ms for transaction processing for the last block of the round

Consensus Changes

• Consensus Changes

API Changes

• API Changes

Documentation Additions

• Documentation Additions

See above.

[jjzhangg]

Can we automatically calculate the percentage based on the CPU performance, and we can control that by setting below configuration in eosio.

1. cpu-frequency-min: 4Ghz
2. cpu-frequency-max: 5Ghz
3. plus, we can refuse to start bp node, when a bp's CPU does not meet the requirement.
4. Still bp can override this percentage by setting in config.ini
   @heifner

[heifner]

@jjzhangg We would like to explore automatically adjusting this setting in a running system. However, tying it to cpu frequency I don't think is any different than this pull request of just setting a percentage. Instead it would be nice to adjust according to latency/load/forks or other heuristics.