mm: meminit: initialise remaining struct pages in parallel with kswapd

Only a subset of struct pages are initialised at the moment.  When this
patch is applied kswapd initialise the remaining struct pages in parallel.

This should boot faster by spreading the work to multiple CPUs and
initialising data that is local to the CPU.  The user-visible effect on
large machines is that free memory will appear to rapidly increase early
in the lifetime of the system until kswapd reports that all memory is
initialised in the kernel log.  Once initialised there should be no other
user-visibile effects.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Tested-by: Nate Zimmer <nzimmer@sgi.com>
Tested-by: Waiman Long <waiman.long@hp.com>
Tested-by: Daniel J Blueman <daniel@numascale.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Robin Holt <robinmholt@gmail.com>
Cc: Nate Zimmer <nzimmer@sgi.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Waiman Long <waiman.long@hp.com>
Cc: Scott Norton <scott.norton@hp.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index e61445dce04e..f4a487110764 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3386,7 +3386,7 @@ static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx)
  * If there are applications that are active memory-allocators
  * (most normal use), this basically shouldn't matter.
  */
-static int kswapd(void *p)
+static int __defermem_init kswapd(void *p)
 {
 	unsigned long order, new_order;
 	unsigned balanced_order;
@@ -3421,6 +3421,8 @@ static int kswapd(void *p)
 	tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
 	set_freezable();
 
+	deferred_init_memmap(pgdat->node_id);
+
 	order = new_order = 0;
 	balanced_order = 0;
 	classzone_idx = new_classzone_idx = pgdat->nr_zones - 1;
@@ -3576,7 +3578,7 @@ static int cpu_callback(struct notifier_block *nfb, unsigned long action,
  * This kswapd start function will be called by init and node-hot-add.
  * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added.
  */
-int kswapd_run(int nid)
+int __defermem_init kswapd_run(int nid)
 {
 	pg_data_t *pgdat = NODE_DATA(nid);
 	int ret = 0;