path: root/init
diff options
authorArjan van de Ven <>2009-01-07 08:45:46 -0800
committerArjan van de Ven <>2009-01-07 08:45:46 -0800
commit22a9d645677feefd402befd02edd59b122289ef1 (patch)
tree9f1215cc8f7f0e1c36b03882b2926cc26ccfa5ff /init
parentede6f5aea054d3fb67c78857f7abdee602302043 (diff)
async: Asynchronous function calls to speed up kernel boot
Right now, most of the kernel boot is strictly synchronous, such that various hardware delays are done sequentially. In order to make the kernel boot faster, this patch introduces infrastructure to allow doing some of the initialization steps asynchronously, which will hide significant portions of the hardware delays in practice. In order to not change device order and other similar observables, this patch does NOT do full parallel initialization. Rather, it operates more in the way an out of order CPU does; the work may be done out of order and asynchronous, but the observable effects (instruction retiring for the CPU) are still done in the original sequence. Signed-off-by: Arjan van de Ven <>
Diffstat (limited to 'init')
2 files changed, 6 insertions, 1 deletions
diff --git a/init/do_mounts.c b/init/do_mounts.c
index 5efca73b39f9..708105e163df 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -13,6 +13,7 @@
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/initrd.h>
+#include <linux/async.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_fs_sb.h>
@@ -372,6 +373,7 @@ void __init prepare_namespace(void)
/* wait for the known devices to complete their probing */
while (driver_probe_done() != 0)
+ async_synchronize_full();
diff --git a/init/main.c b/init/main.c
index b5a892c68375..f66715d8a853 100644
--- a/init/main.c
+++ b/init/main.c
@@ -62,6 +62,7 @@
#include <linux/signal.h>
#include <linux/idr.h>
#include <linux/ftrace.h>
+#include <linux/async.h>
#include <trace/boot.h>
#include <asm/io.h>
@@ -684,7 +685,7 @@ asmlinkage void __init start_kernel(void)
-static int initcall_debug;
+int initcall_debug;
core_param(initcall_debug, initcall_debug, bool, 0644);
int do_one_initcall(initcall_t fn)
@@ -785,6 +786,8 @@ static void run_init_process(char *init_filename)
static noinline int init_post(void)
+ /* need to finish all async __init code before freeing the memory */
+ async_synchronize_full();