block: avoid duplicate calls to get_part() in disk stat code
get_part() is fairly expensive, as it O(N) loops over partitions
to find the right one. In lots of normal IO paths we end up looking
up the partition twice, to make matters even worse. Change the
stat add code to accept a passed in partition instead.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/block/blk-core.c b/block/blk-core.c
index 1b7dddf..2987fe4 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -54,15 +54,16 @@
static void drive_stat_acct(struct request *rq, int new_io)
{
+ struct hd_struct *part;
int rw = rq_data_dir(rq);
if (!blk_fs_request(rq) || !rq->rq_disk)
return;
- if (!new_io) {
- __all_stat_inc(rq->rq_disk, merges[rw], rq->sector);
- } else {
- struct hd_struct *part = get_part(rq->rq_disk, rq->sector);
+ part = get_part(rq->rq_disk, rq->sector);
+ if (!new_io)
+ __all_stat_inc(rq->rq_disk, part, merges[rw], rq->sector);
+ else {
disk_round_stats(rq->rq_disk);
rq->rq_disk->in_flight++;
if (part) {
@@ -1538,10 +1539,11 @@
}
if (blk_fs_request(req) && req->rq_disk) {
+ struct hd_struct *part = get_part(req->rq_disk, req->sector);
const int rw = rq_data_dir(req);
- all_stat_add(req->rq_disk, sectors[rw],
- nr_bytes >> 9, req->sector);
+ all_stat_add(req->rq_disk, part, sectors[rw],
+ nr_bytes >> 9, req->sector);
}
total_bytes = bio_nbytes = 0;
@@ -1727,8 +1729,8 @@
const int rw = rq_data_dir(req);
struct hd_struct *part = get_part(disk, req->sector);
- __all_stat_inc(disk, ios[rw], req->sector);
- __all_stat_add(disk, ticks[rw], duration, req->sector);
+ __all_stat_inc(disk, part, ios[rw], req->sector);
+ __all_stat_add(disk, part, ticks[rw], duration, req->sector);
disk_round_stats(disk);
disk->in_flight--;
if (part) {