llvm/llvm-project

orc::InProcessMemoryMapper makes too many memory mappings

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#63,236 opened on Jun 10, 2023

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good first issuejulialangorcjit

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Description

First seen in https://github.com/JuliaLang/julia/pull/49745, but to summarize, InProcessMemoryMapper calls mprotect many many times on mmaped memory, so many times that for a non trivial workload we go past /proc/sys/vm/max_map_count leading to a ENOMEM error.

I haven't created a non julia reproducer but it should be possible.

Contributor guide

Research direction
Profile the mprotect calls during a workload and identify contiguous memory regions that can be merged to reduce the number of calls.
Tech stack
cpp
Domain
operating systemsperformance
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Mostly clear
Prerequisites
C++Memory Management
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40