Filecoin block/epoch time breakdown

Creator

Alex North

Created

Jun 2, 2023 1:42 AM

From @Łukasz Magiera

Today the ("average worst case") breakdown of an epoch looks something like this:

• T+0 SPs broadcast block for the epoch at T
• T+10 Propagation delay, this much time to get blocks from the network
• T+12 Consistent Broadcast (2s iirc)
• T+17 State compute (if all 5 blocks use whole second for messages each, this is expected to average around 2.5s / epoch)
• Note that this can be a lot higher with network bugs, recent cron bug made this ~12s / epoch
• You'd think that combined with other pessimistic values this would mean that SPs were missing blocks - which is precisely what was happening at that time, to even ~30% of blocks at the time when we had elevated cron times
• T+20 Winning PoSt (Ideally we give SPs slightly larger window, 3s is how long it usually takes, but we'd want even 10s if possible)
• T+21 SPs create blocks (usually subsecond, but occasional mpool issues pushed this to a few seconds)
• T+30 Wait for epoch time to broadcast the block

Now, technically, state compute, winning PoSt and block creation can be done in parallel, but that's not done today