[BLOCK] Unify the seperate read/write io stat fields into arrays
Instead of having ->read_sectors and ->write_sectors, combine the two
into ->sectors[2] and similar for the other fields. This saves a branch
several places in the io path, since we don't have to care for what the
actual io direction is. On my x86-64 box, that's 200 bytes less text in
just the core (not counting the various drivers).
Signed-off-by: Jens Axboe <axboe@suse.de>
diff --git a/drivers/block/ll_rw_blk.c b/drivers/block/ll_rw_blk.c
index 1b27288..2747741 100644
--- a/drivers/block/ll_rw_blk.c
+++ b/drivers/block/ll_rw_blk.c
@@ -2388,10 +2388,7 @@
return;
if (!new_io) {
- if (rw == READ)
- __disk_stat_inc(rq->rq_disk, read_merges);
- else
- __disk_stat_inc(rq->rq_disk, write_merges);
+ __disk_stat_inc(rq->rq_disk, merges[rw]);
} else {
disk_round_stats(rq->rq_disk);
rq->rq_disk->in_flight++;
@@ -2787,17 +2784,11 @@
if (bdev != bdev->bd_contains) {
struct hd_struct *p = bdev->bd_part;
+ const int rw = bio_data_dir(bio);
- switch (bio_data_dir(bio)) {
- case READ:
- p->read_sectors += bio_sectors(bio);
- p->reads++;
- break;
- case WRITE:
- p->write_sectors += bio_sectors(bio);
- p->writes++;
- break;
- }
+ p->sectors[rw] += bio_sectors(bio);
+ p->ios[rw]++;
+
bio->bi_sector += p->start_sect;
bio->bi_bdev = bdev->bd_contains;
}
@@ -3045,10 +3036,9 @@
}
if (blk_fs_request(req) && req->rq_disk) {
- if (rq_data_dir(req) == READ)
- __disk_stat_add(req->rq_disk, read_sectors, nr_bytes >> 9);
- else
- __disk_stat_add(req->rq_disk, write_sectors, nr_bytes >> 9);
+ const int rw = rq_data_dir(req);
+
+ __disk_stat_add(req->rq_disk, sectors[rw], nr_bytes >> 9);
}
total_bytes = bio_nbytes = 0;
@@ -3179,16 +3169,10 @@
if (disk && blk_fs_request(req)) {
unsigned long duration = jiffies - req->start_time;
- switch (rq_data_dir(req)) {
- case WRITE:
- __disk_stat_inc(disk, writes);
- __disk_stat_add(disk, write_ticks, duration);
- break;
- case READ:
- __disk_stat_inc(disk, reads);
- __disk_stat_add(disk, read_ticks, duration);
- break;
- }
+ const int rw = rq_data_dir(req);
+
+ __disk_stat_inc(disk, ios[rw]);
+ __disk_stat_add(disk, ticks[rw], duration);
disk_round_stats(disk);
disk->in_flight--;
}