From 9da057e558369baa9f02b29c400ebabec40705c6 Mon Sep 17 00:00:00 2001
From: oech3 <>
Date: Wed, 3 Jun 2026 11:57:59 +0900
Subject: [PATCH] sum: read ahead for perf for 1st run

---
 Cargo.lock            | 1 +
 src/uu/sum/Cargo.toml | 1 +
 src/uu/sum/src/sum.rs | 2 ++
 3 files changed, 4 insertions(+)

diff --git a/Cargo.lock b/Cargo.lock
index e91623bf5..d7f2d00ac 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4185,6 +4185,7 @@ version = "0.9.0"
 dependencies = [
  "clap",
  "fluent",
+ "rustix",
  "uucore",
 ]
 
diff --git a/src/uu/sum/Cargo.toml b/src/uu/sum/Cargo.toml
index 360597ffc..11b558b57 100644
--- a/src/uu/sum/Cargo.toml
+++ b/src/uu/sum/Cargo.toml
@@ -21,6 +21,7 @@ doctest = false
 
 [dependencies]
 clap = { workspace = true }
+rustix = { workspace = true }
 uucore = { workspace = true }
 fluent = { workspace = true }
 
diff --git a/src/uu/sum/src/sum.rs b/src/uu/sum/src/sum.rs
index d16718612..c4a559e4d 100644
--- a/src/uu/sum/src/sum.rs
+++ b/src/uu/sum/src/sum.rs
@@ -89,6 +89,8 @@ fn open(name: &OsString) -> UResult<Box<dyn Read>> {
             ));
         }
         let f = File::open(path).map_err_context(String::new)?;
+        #[cfg(any(target_os = "linux", target_os = "android", target_os = "freebsd"))]
+        let _ = rustix::fs::fadvise(&f, 0, None, rustix::fs::Advice::Sequential);
         Ok(Box::new(f) as Box<dyn Read>)
     }
 }