Share memory reduction logic and enable compaction for WSLC#40376
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Share memory reduction logic and enable compaction for WSLC#40376
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Pull request overview
This PR refactors the Linux init memory-reduction logic so it can be shared between the WSL2 init (main.cpp) and WSLC init (WSLCInit.cpp), and enables idle-time compaction + cache dropping for WSLC VMs.
Changes:
- Introduces a shared
UtilStartMemoryReductionThread()entry point inutil.cppand aMemoryReductionModeenum inutil.h. - Updates WSL2 init’s
ConfigureMemoryReduction()to delegate to the shared thread logic. - Starts the memory reduction thread in WSLC init with drop-caches behavior when idle.
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated 6 comments.
| File | Description |
|---|---|
| src/linux/init/util.h | Adds MemoryReductionMode and the shared thread API declaration. |
| src/linux/init/util.cpp | Implements shared idle monitoring + compaction/reclaim thread and moves helpers into util. |
| src/linux/init/main.cpp | Replaces local memory reduction thread logic with a call into UtilStartMemoryReductionThread(). |
| src/linux/init/WSLCInit.cpp | Enables memory reduction thread for WSLC init (drop caches + compaction when idle). |
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OneBlue
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May 4, 2026
Extract the memory compaction and cache reclaim thread into StartMemoryReductionThread() in util.cpp. WSLC now runs the same idle-based compaction and drop_caches logic that WSL2 uses, improving page reporting efficiency and reducing host memory pressure. - Add StartMemoryReductionThread() and MemoryReductionMode to util.h/cpp - WSL2 main.cpp delegates to shared implementation - WSLC WSLCInit.cpp calls StartMemoryReductionThread(DropCache) - Remove duplicated GetUserCpuTime/GetMemoryInUse from main.cpp Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
… directly Address PR review feedback: - Remove redundant MemoryReductionMode enum and use the existing wire enum LX_MINI_INIT_MEMORY_RECLAIM_MODE directly, eliminating the unsafe static_cast that could have swapped Gradual/DropCache behavior. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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ProcessMessages may MS_MOVE /proc into the chroot target before invoking chroot(); starting the thread before that window risked failing path lookups under /proc. Defer the thread start until the first successful chroot, guarded by a once_flag so subsequent mount messages don't re-start. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Summary
This PR refactors the Linux init memory-reduction logic so it can be shared between the WSL2 init (
main.cpp) and WSLC init (WSLCInit.cpp), and enables idle-time compaction + cache dropping for WSLC VMs.Changes
StartMemoryReductionThread(LX_MINI_INIT_MEMORY_RECLAIM_MODE)entry point inutil.cpp.GetUserCpuTimeandGetMemoryInUsehelpers toutil.cppas file-local (static) functions.StartMemoryReductionThreaddirectly instead of going throughConfigureMemoryReduction().LX_MINI_INIT_MEMORY_RECLAIM_MODEwire enum directly rather than introducing a separate enum.Notes