[PATCH] swsusp: read speedup

Implement async reads for swsusp resuming.

Crufty old PIII testbox:
	15.7 MB/s -> 20.3 MB/s

Sony Vaio:
	14.6 MB/s -> 33.3 MB/s

I didn't implement the post-resume bio_set_pages_dirty().  I don't really
understand why resume needs to run set_page_dirty() against these pages.

It might be a worry that this code modifies PG_Uptodate, PG_Error and
PG_Locked against the image pages.  Can this possibly affect the resumed-into
kernel?  Hopefully not, if we're atomically restoring its mem_map?

Cc: Pavel Machek <pavel@ucw.cz>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Jens Axboe <axboe@suse.de>
Cc: Laurent Riffard <laurent.riffard@free.fr>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 8 insertions, 3 deletions

diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 75d4886e648e..591301ae8b7d 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -314,7 +314,7 @@ static unsigned int unsafe_pages;
  *      and we count them using unsafe_pages
  */
 
-static inline void *alloc_image_page(gfp_t gfp_mask, int safe_needed)
+static void *alloc_image_page(gfp_t gfp_mask, int safe_needed)
 {
         void *res;
 
@@ -828,13 +828,16 @@ int snapshot_write_next(struct snapshot_handle *handle, size_t count)
         }
         if (!handle->offset)
                 handle->buffer = buffer;
+        handle->sync_read = 1;
         if (handle->prev < handle->page) {
                 if (!handle->prev) {
-                        error = load_header(handle, (struct swsusp_info *)buffer);
+                        error = load_header(handle,
+                                        (struct swsusp_info *)buffer);
                         if (error)
                                 return error;
                 } else if (handle->prev <= nr_meta_pages) {
-                        handle->pbe = unpack_orig_addresses(buffer, handle->pbe);
+                        handle->pbe = unpack_orig_addresses(buffer,
+                                                        handle->pbe);
                         if (!handle->pbe) {
                                 error = prepare_image(handle);
                                 if (error)
@@ -842,10 +845,12 @@ int snapshot_write_next(struct snapshot_handle *handle, size_t count)
                                 handle->pbe = pagedir_nosave;
                                 handle->last_pbe = NULL;
                                 handle->buffer = get_buffer(handle);
+                                handle->sync_read = 0;
                         }
                 } else {
                         handle->pbe = handle->pbe->next;
                         handle->buffer = get_buffer(handle);
+                        handle->sync_read = 0;
                 }
                 handle->prev = handle->page;
         }