bench: Allow configuring the runtime type in the bulk bench

[rklaehn]

Description

Allow configuring the runtime type in the bulk bench

Also switch the default to the multithreaded runtime. I think that is more representative of actual use.

I mostly need this to compare the two runtimes. Currently the current thread runtime is faster, which is very unintuitive, since we are doing absolutely everything on one thread, send, recv, encrypt, decrypt.

Breaking Changes

None

Notes & open questions

[github-actions]

Documentation for this PR has been generated and is available at: https://n0-computer.github.io/quinn/pr/280/docs/iroh_quinn/

Last updated: 2025-12-19T15:00:26Z

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 21 lines in your changes missing coverage. Please review.
✅ Project coverage is 76.47%. Comparing base (4dcb3a7) to head (225bd3e).
⚠️ Report is 32 commits behind head on main.

Files with missing lines	Patch %	Lines
bench/src/lib.rs	0.00%	19 Missing ⚠️
bench/src/bin/bulk.rs	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #280      +/-   ##
==========================================
- Coverage   76.69%   76.47%   -0.22%     
==========================================
  Files          83       83              
  Lines       23241    23352     +111     
==========================================
+ Hits        17824    17858      +34     
- Misses       5417     5494      +77     

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[flub]

@matheus23 could you review this please?

[matheus23]

In iroh-bench I'm doing some very similar changes, can we align on them? There, I allow configuring the amount of worker threads per endpoint.
IMO this is slightly better than configuring all endpoints to have a multi-threaded runtime, since then you'd be putting multiple full-sized tokio runtimes into a single process.
I've added an admittedly somewhat hacky fallback there where setting --workers-per-ep=0 will use the normal multi-threaded runtime.