From 6ff84da11affcf6b10ef6f8673fde1284c3a4567 Mon Sep 17 00:00:00 2001 From: Surbhi Palande Date: Tue, 8 Dec 2009 11:44:34 +0200 Subject: [PATCH] UBUNTU: SAUCE: Make populate_rootfs asynchronous The expansion of the initramfs is completely independant of other boot activities. The original data is already present at boot and the filesystem is not required until we are ready to start init. It is therefore reasonable to populate the rootfs asynchronously. Move this processing to an async call. This reduces kernel initialisation time (the time from bootloader to starting userspace) by several 10ths of a second on a selection of test hardware particularly SMP systems, although UP system also benefit. Signed-off-by: Surbhi Palande Signed-off-by: Andy Whitcroft --- include/linux/init.h | 2 ++ init/initramfs.c | 15 ++++++++++++--- init/main.c | 6 ++++++ 3 files changed, 20 insertions(+), 3 deletions(-) diff --git a/include/linux/init.h b/include/linux/init.h index 9146f39..a2b5b8a 100644 --- a/include/linux/init.h +++ b/include/linux/init.h @@ -222,6 +222,8 @@ extern int initcall_debug; static initcall_t __initcall_##fn \ __used __section(.security_initcall.init) = fn +extern struct list_head populate_rootfs_domain; + struct obs_kernel_param { const char *str; int (*setup_func)(char *); diff --git a/init/initramfs.c b/init/initramfs.c index 2531811..22712f9 100644 --- a/init/initramfs.c +++ b/init/initramfs.c @@ -8,6 +8,7 @@ #include #include #include +#include static __initdata char *message; static void __init error(char *x) @@ -569,7 +570,9 @@ static void __init clean_rootfs(void) } #endif -static int __init populate_rootfs(void) +LIST_HEAD(populate_rootfs_domain); + +static void __init async_populate_rootfs(void) { char *err = unpack_to_rootfs(__initramfs_start, __initramfs_size); if (err) @@ -582,7 +585,7 @@ static int __init populate_rootfs(void) initrd_end - initrd_start); if (!err) { free_initrd(); - return 0; + return; } else { clean_rootfs(); unpack_to_rootfs(__initramfs_start, __initramfs_size); @@ -606,6 +609,12 @@ static int __init populate_rootfs(void) free_initrd(); #endif } - return 0; + return; } + +static int __init populate_rootfs(void) +{ + async_schedule_domain(async_populate_rootfs, NULL, &populate_rootfs_domain); +} + rootfs_initcall(populate_rootfs); diff --git a/init/main.c b/init/main.c index 70c5b0a..1c691f9 100644 --- a/init/main.c +++ b/init/main.c @@ -811,6 +811,12 @@ static int __init kernel_init(void * unused) (void) sys_dup(0); (void) sys_dup(0); /* + * We need to ensure that the filesystem is ready by this point, wait for + * async_populate_rootfs to complete. + */ + async_synchronize_full_domain(&populate_rootfs_domain); + + /* * check if there is an early userspace init. If yes, let it do all * the work */ -- 1.7.0.4