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Add FADV_RANDOM to accountsdb appendvec impl #9846

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Add FADV_RANDOM to accountsdb appendvec impl #9846

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1 change: 1 addition & 0 deletions Cargo.lock
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1 change: 1 addition & 0 deletions accounts-db/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,7 @@ crossbeam-channel = { workspace = true }
dashmap = { workspace = true, features = ["rayon", "raw-api"] }
indexmap = { workspace = true }
itertools = { workspace = true }
libc = { workspace = true }
log = { workspace = true }
lz4 = { workspace = true }
memmap2 = { workspace = true }
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7 changes: 7 additions & 0 deletions accounts-db/src/append_vec.rs
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Expand Up @@ -41,6 +41,7 @@ use {
fs::{remove_file, File, OpenOptions},
io::{self, BufRead, Seek, SeekFrom, Write},
mem::{self, MaybeUninit},
os::fd::{AsFd, AsRawFd},
path::{Path, PathBuf},
ptr, slice,
sync::{
Expand Down Expand Up @@ -262,6 +263,12 @@ impl AppendVec {
})
.unwrap();

// tell the kernel that we expect to randomly access the file and not to bother using
// page cache and reading ahead
unsafe {
libc::posix_fadvise(data.as_fd().as_raw_fd(), 0, 0, libc::POSIX_FADV_RANDOM);
}

// Theoretical performance optimization: write a zero to the end of
// the file so that we won't have to resize it later, which may be
// expensive.
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