perf: enable demand paging for heap (3 GiB → 654 MiB snapshots) - #100
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perf: enable demand paging for heap (3 GiB → 654 MiB snapshots)#100danbugs wants to merge 1 commit into
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Linux Benchmarks
Details
| Benchmark suite | Current: 307f19b | Previous: 4460ae2 | Ratio |
|---|---|---|---|
hello_world (median) |
20 ms |
20 ms |
1 |
pandas (median) |
110 ms |
110 ms |
1 |
density (per VM) |
8 MB |
11 MB |
0.73 |
snapshot (disk) |
653 MiB |
656 MiB |
1.00 |
This comment was automatically generated by workflow using github-action-benchmark.
Temporarily point all examples' unikraft source at danbugs/unikraft:perf/demand-page-heap to validate the boot.c heap unmap fix across all examples. This branch adds a uk_paging_page_unmap call after uk_vma_map_anon in heap_init(), tearing down boot-provided identity-mapped PTEs so demand paging works correctly. Reduces snapshot size from 3.0 GiB to 654 MiB for Python guests. Signed-off-by: danbugs <danilochiarlone@gmail.com>
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Windows Benchmarks
Details
| Benchmark suite | Current: 307f19b | Previous: 4460ae2 | Ratio |
|---|---|---|---|
hello_world (median) |
151 ms |
301 ms |
0.50 |
pandas (median) |
546 ms |
768 ms |
0.71 |
density (per VM) |
328 MB |
656 MB |
0.50 |
snapshot (disk) |
654 MiB |
664 MiB |
0.98 |
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No longer needed — demand-page-heap testing covered in PR 99 |
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Summary
danbugs/unikraft:perf/demand-page-heap, which adds auk_paging_page_unmapcall inboot.c:heap_init()to tear down boot-provided identity-mapped PTEs after setting up the demand-paged VMASnapshot::from_env()identity-maps the entire heap in boot page tables before the guest starts. Unikraft'suk_vma_map_anoncreates a demand-paged VMA on top but never removes the existing PTEs, sovma_op_anon_faultnever fires and all heap pages (including untouched zeroes) end up in the snapshotTest plan