Cannot use more than 128 parallel streams

Open Beginner friendly
  • Is something wrong?
#2,079 3 comments 0 reactions 0 assignees View on GitHub

Maintainers usually reply within 2 days

@davidBar-On is already working on this.

Since Oct 1, 2026.

  • #2084 by @davidBar-On — open

Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
72/100
Issue type
Feature
Clarity
Mostly clear
Activity status
Active
Tech stack
c
Domain
cli, networking

Research direction

Start by locating the C code that parses or validates the -P parallel-stream option and identify where the value 128 is enforced. Update the supported maximum to 256, then verify that values through -P 256 are accepted and that the existing limit behavior remains covered by the project's tests.

Written by the indexing model from the issue text.

Description

I have a use case that calls for generating more than 128 streams of traffic, currently it appears values beyond -P 128 are not supported.

Is there any reason why this can't be increased? Would you be open to a PR that bumps this to say 256?

Dominant language
C
Stars
8.9k
Forks
1.5k
Avg merge
5d 11h
Merged PRs (30d)
2

Getting set up

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

More from esnet/iperf

All issues in esnet/iperf

Similar issues

More C issues

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.