Use maximum allowed response size for request/response protocols

[AndreiEres]

Description

Adjust the PoV response size to the default values used in the substrate.
Fixes #5503

Integration

The changes shouldn't impact downstream projects since we are only increasing the limit.

Review Notes

You can't see it from the changes, but it affects all protocols that use the POV_RESPONSE_SIZE constant.

• Protocol::ChunkFetchingV1
• Protocol::ChunkFetchingV2
• Protocol::CollationFetchingV1
• Protocol::CollationFetchingV2
• Protocol::PoVFetchingV1
• Protocol::AvailableDataFetchingV1

Increasing timeouts

polkadot-sdk/polkadot/node/network/protocol/src/request_response/mod.rs

Lines 126 to 129 in fae1537

	/// This timeout is based on what seems sensible from a time budget perspective, considering 6
	/// second block time. This is going to be tough, if we have multiple forks and large PoVs, but we
	/// only have so much time.
	const POV_REQUEST_TIMEOUT_CONNECTED: Duration = Duration::from_millis(1200);

I assume the current PoV request timeout is set to 1.2s to handle 5 consecutive requests during a 6s block. This setting does not relate to the PoV response size. I see no reason to change the current timeouts after adjusting the response size.

However, we should consider networking speed limitations if we want to increase the maximum PoV size to 10 MB. With the number of parallel requests set to 10, validators will need the following networking speeds:

• 5 MB PoV: at least 42 MB/s, ideally 50 MB/s.
• 10 MB PoV: at least 84 MB/s, ideally 100 MB/s.

The current required speed of 50 MB/s aligns with the 62.5 MB/s specified in the reference hardware requirements. Increasing the PoV size to 10 MB may require a higher networking speed.

[sandreim]

PRDoc ?

[sandreim]

I think substrate should export a constant and we should use it here.

[sandreim]

The current required speed of 50 MB/s aligns with the 62.5 MB/s specified in the reference hardware requirements. Increasing the PoV size to 10 MB may require a higher networking speed.

Yes, this is worst case scenario, when all blocks you need to recover are full. We'll likely have to raise specs for networking,

[dmitry-markin]

Is it safe to not base this value on MAX_POV_SIZE?

[AndreiEres]

It's okay, I suppose, because we make these changes to bump it.

[sandreim]

The current required speed of 50 MB/s aligns with the 62.5 MB/s specified in the reference hardware requirements. Increasing the PoV size to 10 MB may require a higher networking speed.

Yes, this is worst case scenario, when all blocks you need to recover are full. We'll likely have to raise specs for networking,

Did a bit of math in #5334 (comment) . looks like we should be fine.