microsoft / microsoft/usersim

KeSetTimer doesn't fire when there is a heavy DPC load

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#189 2 comments 0 reactions 0 assignees View on GitHub

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Dominant language
C++
Stars
105
Forks
34
Avg merge
3d 39m
Merged PRs (30d)
5

Description

Emulated DPC threads running at thread priority time critical which starves the thread pool timer threads resulting in the timers not firing.

This breaks the eBPF for Windows epoch cleanup code which requires a timer to initiate.

Contributor guide

Open the contributing guide

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.

Research direction

Start by tracing the emulated KeSetTimer path alongside the emulated DPC threads and thread pool timer threads. Reproduce the behavior under heavy DPC load, then verify that timers fire and the eBPF for Windows epoch cleanup code can initiate its timer-driven cleanup.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
operating-systems
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
42/100

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