seg: read-ahead implemented as own mmap area + madvise_ (only concept, no erigon changes)#19397
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AskAlexSharov merged 15 commits intomainfrom Feb 24, 2026
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seg: read-ahead implemented as own mmap area + madvise_ (only concept, no erigon changes)#19397AskAlexSharov merged 15 commits intomainfrom
mmap area + madvise_ (only concept, no erigon changes)#19397AskAlexSharov merged 15 commits intomainfrom
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mmap regionmmap area + madvise_ (only concept, no erigon changes)
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…cept, no erigon changes) (#19397) Context: merge is slow becuse it reading large files `mmap'ed` by `MADV_RANDOM`. Idea: It's possible to have 1 `file-descriptor` with N `VMA` (Virtual Memory Area). In another word: `mmap` many time same file. Means each `mmap` can have own `MADVISE_*` hints: - all existing RPC requrests and ChainTip will go to existing `mmap` area (MADV_RANDOM). - merge will go to new temporary `mmap` area (MADV_NORMAL). existing RPC will not hit it. overall 3gb file on raid of 4 nvme: `15s -> 3.7s`. But impact impact on exec perf need to test. Also usually files are warm-enough to make speedup of `merge` less than "read cold file in wacuum". Will see. Also `accessor build` likely will benefit from same thing.
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Context: merge is slow becuse it reading large files
mmap'edbyMADV_RANDOM.Idea: It's possible to have 1
file-descriptorwith NVMA(Virtual Memory Area). In another word:mmapmany time same file.Means each
mmapcan have ownMADVISE_*hints:mmaparea (MADV_RANDOM).mmaparea (MADV_NORMAL). existing RPC will not hit it.overall 3gb file on raid of 4 nvme:
15s -> 3.7s. But impact impact on exec perf need to test. Also usually files are warm-enough to make speedup ofmergeless than "read cold file in wacuum".Will see. Also
accessor buildlikely will benefit from same thing.