Michael Opdenacker contributed a readahead applet.
diff --git a/miscutils/Config.in b/miscutils/Config.in
index 4296b54..9ad3421 100644
--- a/miscutils/Config.in
+++ b/miscutils/Config.in
@@ -276,6 +276,22 @@
to advance or rewind a tape past a specified number of archive
files on the tape.
+config CONFIG_READAHEAD
+ bool "readahead"
+ default n
+ help
+ Preload the files listed on the command line into RAM cache so that
+ subsequent reads on these files will not block on disk I/O.
+
+ This applet just calls the readahead(2) system call on each file.
+ It is mainly useful in system startup scripts to preload files
+ or executables before they are used. When used at the right time
+ (in particular when a CPU boundprocess is running) it can
+ significantly speed up system startup.
+
+ As readahead(2) blocks until each file has been read, it is best to
+ run this applet as a background job.
+
config CONFIG_RUNLEVEL
bool "runlevel"
default n
diff --git a/miscutils/Makefile.in b/miscutils/Makefile.in
index a0b6b72..25143c1 100644
--- a/miscutils/Makefile.in
+++ b/miscutils/Makefile.in
@@ -24,6 +24,7 @@
MISCUTILS-$(CONFIG_MAKEDEVS) += makedevs.o
MISCUTILS-$(CONFIG_MOUNTPOINT) += mountpoint.o
MISCUTILS-$(CONFIG_MT) += mt.o
+MISCUTILS-$(CONFIG_READAHEAD) += readahead.o
MISCUTILS-$(CONFIG_RUNLEVEL) += runlevel.o
MISCUTILS-$(CONFIG_RX) += rx.o
MISCUTILS-$(CONFIG_SETSID) += setsid.o
diff --git a/miscutils/readahead.c b/miscutils/readahead.c
new file mode 100644
index 0000000..9f1bb47
--- /dev/null
+++ b/miscutils/readahead.c
@@ -0,0 +1,36 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * readahead implementation for busybox
+ *
+ * Preloads the given files in RAM, to reduce access time.
+ * Does this by calling the readahead(2) system call.
+ *
+ * Copyright (C) 2006 Michael Opdenacker <michael@free-electrons.com>
+ *
+ * Licensed under GPLv2 or later, see file License in this tarball for details.
+ */
+
+#include "busybox.h"
+
+int readahead_main(int argc, char **argv)
+{
+ FILE *f;
+ struct stat stat_buf;
+ int retval = EXIT_SUCCESS;
+
+ if (argc == 1) bb_show_usage();
+
+ while (*++argv) {
+ if ((f = bb_wfopen(*argv, "r")) != NULL) {
+ int r, fd=fileno(f);
+
+ xstat(*argv, &stat_buf);
+ r = readahead(fd, 0, fdlength(fd));
+ fclose(f);
+ if (r >= 0) continue;
+ }
+ retval = EXIT_FAILURE;
+ }
+
+ return retval;
+}