Improve `parachains_paras_inherent` and `Coretime` benchmarks initialization

[bkontur]

Identified in the fellows repo: https://github.com/polkadot-fellows/runtimes/actions/runs/15685983106/job/44189322905

2025-06-17T05:37:17.691857Z  WARN runtime::parachains: Took active validators from set with wrong size    
2025-06-17T05:37:17.691942Z ERROR runtime::parachains::coretime: Sending `NotifyCoreCount` to coretime chain failed: Unroutable    
2025-06-17T05:37:20.845511Z  WARN runtime::inclusion-inherent: ParentBlockRandomness did not provide entropy    
2025-06-17T05:37:22.418110Z  WARN runtime::parachains: Took active validators from set with wrong size    
2025-06-17T05:37:22.418187Z  WARN runtime::parachains: Took active validators from set with wrong size    
2025-06-17T05:37:22.418190Z  WARN runtime::parachains: Took active validators from set with wrong size.    
2025-06-17T05:37:22.418208Z  WARN runtime::parachains: Took active validators from set with wrong size    
2025-06-17T05:37:22.418487Z  WARN runtime::parachains: Took active validators from set with wrong size    
2025-06-17T05:37:22.418531Z  WARN runtime::parachains: Took active validators from set with wrong size    
2025-06-17T05:37:22.418533Z  WARN runtime::parachains: Took active validators from set with wrong size.    
2025-06-17T05:37:22.418550Z  WARN runtime::parachains: Took active validators from set with wrong size    
2025-06-17T05:37:22.418893Z  WARN runtime::parachains: Took active validators from set with wrong size    
2025-06-17T05:37:22.418950Z  WARN runtime::parachains: Took active validators from set with wrong size    
2025-06-17T05:37:22.418956Z  WARN runtime::parachains: Took active validators from set with wrong size.    
2025-06-17T05:37:22.418979Z  WARN runtime::parachains: Took active validators from set with wrong size    
2025-06-17T05:37:22.419068Z ERROR runtime::parachains::coretime: Sending `NotifyCoreCount` to coretime chain failed: Unroutable    
2025-06-17T05:37:25.623200Z  WARN runtime::inclusion-inherent: ParentBlockRandomness did not provide entropy    

There are couple of errors:

Sending `NotifyCoreCount` to coretime chain failed: Unroutable`

which are caused by coretime::Config module used as type CoretimeOnNewSession = Coretime;. The error is generated by this code:
https://github.com/paritytech/polkadot-sdk/blob/master/polkadot/runtime/parachains/src/coretime/mod.rs#L271-L275, when sending XCMs with send_xcm, this coretime module sends also other XCMs, but all to the same location: Location::new(0, [Junction::Parachain(T::BrokerId::get())]),.

So as the possible fix, would be to trigger for benchmarks:

coretime/mod.rs

<T as coretime::Contig>::SendXcm::ensure_successful_delivery(
        Some(
                Location::new(0, [Junction::Parachain(<T as coretime::Contig>::BrokerId::get())])
        )
);

or alternatively:

// This could is exactly triggered with `ensure_successful_delivery` above - I prefere the above solution
Dmp::make_parachain_reachable(<T as coretime::Contig>::BrokerId);

But the problem is that, we need to find a best place where to trigger mentioned above solutions.
For paras::inherent benchmarks looks like the best place is BenchBuilder::build function here,
but paras::inherent::Config does not have direct reference to the coretime::Config (only through initialiezer's CoretimeOnNewSession), so we cannot access neither coretime::Config::SendXcm nor coretime::Config::BrokerId.

TODO

• fix paras::inherent benchmarking error - potential issue that ChildParachainRouter or Dmp weights might not be included in the total weights
• fix/check all other benchmarks that use/hit coretime::Config::SendXcm

[EleisonC]

Hi @bkontur, I’m wondering if this task is still available. I'd like to take it on

[bkontur]

Hi @bkontur, I’m wondering if this task is still available. I'd like to take it on

@EleisonC Yes, of course, any help is welcome :) But before you start coding, please investigate the issue and propose a solution first, okay? So, we can discuss the direction before coding.

[mh07607]

Hi @bkontur , I wanted to understand and work on this task if that's possible. The first question I have is that where can I reproduce the log that you shared with the fellows repo link?

[EleisonC]

Hey @mh07607 currently working on this