rr-debugger / rr-debugger/rr

Use desched event for all task scheduling

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#799 0 comments 0 reactions 0 assignees View on GitHub

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Dominant language
C++
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Description

Thought I'd filed this, but I guess not.

The machinery we've built for monitoring desched's could actually be made quite general. If we arm the event when a tracee is scheduled, then we could just let the tracee run until either it traps to a traced syscall, or the desched event fires. This would let the kernel do most of rr's task scheduling for it.

It would also make eliminate the notion of a may-block syscall from syscallbuf, making things much simpler and potentially more efficient. The desched event would always be armed, so any buffered syscall could potentially fire the event.

The mechanics of arming and disarming the event from within the tracer are a bit tricky, but I think doable.

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First steps

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Research direction

The issue names no files or tests. Start by tracing the existing desched-event monitoring and syscallbuf scheduling machinery; done means the desched event is always armed for scheduled tracees and the may-block syscall concept is removed without disrupting traced-syscall handling.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp, linux
Domain
devtools, operating-systems
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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