[PATCH] swsusp: add write-speed instrumentation

Add some instrumentation to the swsusp writeout code to show what bandwidth
we're achieving.

Cc: Pavel Machek <pavel@ucw.cz>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 29 insertions, 3 deletions

diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index f1dd146bd64d..79b66e734bdb 100644
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -146,6 +146,26 @@ static void release_swap_writer(struct swap_map_handle *handle)
         handle->bitmap = NULL;
 }
 
+static void show_speed(struct timeval *start, struct timeval *stop,
+                        unsigned nr_pages, char *msg)
+{
+        s64 elapsed_centisecs64;
+        int centisecs;
+        int k;
+        int kps;
+
+        elapsed_centisecs64 = timeval_to_ns(stop) - timeval_to_ns(start);
+        do_div(elapsed_centisecs64, NSEC_PER_SEC / 100);
+        centisecs = elapsed_centisecs64;
+        if (centisecs == 0)
+                centisecs = 1;  /* avoid div-by-zero */
+        k = nr_pages * (PAGE_SIZE / 1024);
+        kps = (k * 100) / centisecs;
+        printk("%s %d kbytes in %d.%02d seconds (%d.%02d MB/s)\n", msg, k,
+                        centisecs / 100, centisecs % 100,
+                        kps / 1000, (kps % 1000) / 10);
+}
+
 static int get_swap_writer(struct swap_map_handle *handle)
 {
         handle->cur = (struct swap_map_page *)get_zeroed_page(GFP_KERNEL);
@@ -206,17 +226,21 @@ static int flush_swap_writer(struct swap_map_handle *handle)
 
 static int save_image(struct swap_map_handle *handle,
                       struct snapshot_handle *snapshot,
-                      unsigned int nr_pages)
+                      unsigned int nr_to_write)
 {
         unsigned int m;
         int ret;
         int error = 0;
+        int nr_pages;
+        struct timeval start;
+        struct timeval stop;
 
-        printk("Saving image data pages (%u pages) ...     ", nr_pages);
-        m = nr_pages / 100;
+        printk("Saving image data pages (%u pages) ...     ", nr_to_write);
+        m = nr_to_write / 100;
         if (!m)
                 m = 1;
         nr_pages = 0;
+        do_gettimeofday(&start);
         do {
                 ret = snapshot_read_next(snapshot, PAGE_SIZE);
                 if (ret > 0) {
@@ -228,8 +252,10 @@ static int save_image(struct swap_map_handle *handle,
                         nr_pages++;
                 }
         } while (ret > 0);
+        do_gettimeofday(&stop);
         if (!error)
                 printk("\b\b\b\bdone\n");
+        show_speed(&start, &stop, nr_to_write, "Wrote");
         return error;
 }