[ExecuTorch][MmapDataLoader] Issue F_RDADVISE on Apple platforms in UseMadvise path#19554
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[ExecuTorch][MmapDataLoader] Issue F_RDADVISE on Apple platforms in UseMadvise path#19554kimishpatel wants to merge 2 commits into
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…seMadvise path In the MmapDataLoader UseMadvise codepath, after the existing madvise(MADV_WILLNEED | MADV_SEQUENTIAL) calls, also issue fcntl(F_RDADVISE) on Apple platforms (iOS/macOS). F_RDADVISE is more aggressive than madvise for cold starts: it schedules read-ahead on the file descriptor itself, bringing pages into the unified buffer cache so first-touch faults during inference are serviced from RAM instead of storage. F_RDADVISE closes part of the gap between lazy mmap and eager file read, while still allowing pages to be evicted under memory pressure (unlike mlock, which pins pages and counts against RLIMIT_MEMLOCK). Differential Revision: [D104318326](https://our.internmc.facebook.com/intern/diff/D104318326/) [ghstack-poisoned]
🔗 Helpful Links🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/19554
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…tforms in UseMadvise path" In the MmapDataLoader UseMadvise codepath, after the existing madvise(MADV_WILLNEED | MADV_SEQUENTIAL) calls, also issue fcntl(F_RDADVISE) on Apple platforms (iOS/macOS). F_RDADVISE is more aggressive than madvise for cold starts: it schedules read-ahead on the file descriptor itself, bringing pages into the unified buffer cache so first-touch faults during inference are serviced from RAM instead of storage. F_RDADVISE closes part of the gap between lazy mmap and eager file read, while still allowing pages to be evicted under memory pressure (unlike mlock, which pins pages and counts against RLIMIT_MEMLOCK). Differential Revision: [D104318326](https://our.internmc.facebook.com/intern/diff/D104318326/) [ghstack-poisoned]
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…seMadvise path Pull Request resolved: #19554 In the MmapDataLoader UseMadvise codepath, after the existing madvise(MADV_WILLNEED | MADV_SEQUENTIAL) calls, also issue fcntl(F_RDADVISE) on Apple platforms (iOS/macOS). F_RDADVISE is more aggressive than madvise for cold starts: it schedules read-ahead on the file descriptor itself, bringing pages into the unified buffer cache so first-touch faults during inference are serviced from RAM instead of storage. F_RDADVISE closes part of the gap between lazy mmap and eager file read, while still allowing pages to be evicted under memory pressure (unlike mlock, which pins pages and counts against RLIMIT_MEMLOCK). Differential Revision: [D104318326](https://our.internmc.facebook.com/intern/diff/D104318326/) ghstack-source-id: 381778987
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Stack from ghstack (oldest at bottom):
In the MmapDataLoader UseMadvise codepath, after the existing
madvise(MADV_WILLNEED | MADV_SEQUENTIAL) calls, also issue fcntl(F_RDADVISE)
on Apple platforms (iOS/macOS). F_RDADVISE is more aggressive than madvise
for cold starts: it schedules read-ahead on the file descriptor itself,
bringing pages into the unified buffer cache so first-touch faults during
inference are serviced from RAM instead of storage.
F_RDADVISE closes part of the gap between lazy mmap and eager file read,
while still allowing pages to be evicted under memory pressure (unlike
mlock, which pins pages and counts against RLIMIT_MEMLOCK).
Differential Revision: D104318326