cat: avoid fcntl with smaller files

Author: oech3

src/uu/cat/src/splice.rs

@@ -24,16 +24,16 @@ pub(super) fn write_fast_using_splice<R: FdReadable, S: AsRawFd + AsFd>(
     write_fd: &S,
 ) -> CatResult<bool> {
     use nix::fcntl::{FcntlArg, fcntl};
-    // improve performance
-    if fcntl(
-        write_fd,
-        FcntlArg::F_SETPIPE_SZ(MAX_ROOTLESS_PIPE_SIZE as i32),
-    )
-    .is_ok()
-    {
+    const FIRST_PIPE_SIZE: usize = 64 * 1024;
+    if splice(&handle.reader, &write_fd, FIRST_PIPE_SIZE).is_ok() {
+        // fcntl improves performance for large file which is large overhead for small files
+        let _ = fcntl(
+            write_fd,
+            FcntlArg::F_SETPIPE_SZ(MAX_ROOTLESS_PIPE_SIZE as i32),
+        );
         loop {
             match splice(&handle.reader, &write_fd, MAX_ROOTLESS_PIPE_SIZE) {
-                Ok(1..) => {},
+                Ok(1..) => {}
                 Ok(0) => return Ok(false),
                 Err(_) => return Ok(true),
             }