[patch] optimize disk_round_stats

[Chen, Kenneth W]

Following the same idea, it occurs to me that we should only update
disk stat when "now" is different from disk->stamp.  Otherwise, we
are again needlessly adding zero to the stats.


Signed-off-by: Ken Chen <kenneth.w.chen@xxxxxxxxx>

--- ./drivers/block/ll_rw_blk.c.orig	2005-10-13 11:54:07.474907379 -0700
+++ ./drivers/block/ll_rw_blk.c	2005-10-13 11:54:39.074516367 -0700
@@ -2433,6 +2433,9 @@ void disk_round_stats(struct gendisk *di
 {
 	unsigned long now = jiffies;
 
+	if (now == disk->stamp)
+		return;
+
 	if (disk->in_flight) {
 		__disk_stat_add(disk, time_in_queue,
 				disk->in_flight * (now - disk->stamp));



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