[PATCH 1/2] Block: Disable polling stats when iostats are disabled

[Jon Derrick]

Extends iostats to encompass polling statistics to save a few cycles
when disabled.

Signed-off-by: Jon Derrick <jonathan.derrick at intel.com>
---
 block/blk-core.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index ab51685..354d03b 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -3350,13 +3350,16 @@ bool blk_poll(struct request_queue *q, blk_qc_t cookie)
 	while (!need_resched()) {
 		unsigned int queue_num = blk_qc_t_to_queue_num(cookie);
 		struct blk_mq_hw_ctx *hctx = q->queue_hw_ctx[queue_num];
+		int io_stat = blk_queue_io_stat(q);
 		int ret;
 
-		hctx->poll_invoked++;
+		if (io_stat)
+			hctx->poll_invoked++;
 
 		ret = q->mq_ops->poll(hctx, blk_qc_t_to_tag(cookie));
 		if (ret > 0) {
-			hctx->poll_success++;
+			if (io_stat)
+				hctx->poll_success++;
 			set_current_state(TASK_RUNNING);
 			return true;
 		}
-- 
1.8.3.1