block: add poll_considered statistic

In order to help determine the effectiveness of polling in a running
system it is usful to determine the ratio of how often the poll
function is called vs how often the completion is checked. For this
reason we add a poll_considered variable and add it to the sysfs entry
for io_poll.

Signed-off-by: Stephen Bates <sbates@raithlin.com>
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index e1544f0f8c21..7710f795d7c2 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -61,6 +61,7 @@ struct blk_mq_hw_ctx {
         struct blk_mq_cpu_notifier      cpu_notifier;
         struct kobject          kobj;
 
+        unsigned long           poll_considered;
         unsigned long           poll_invoked;
         unsigned long           poll_success;
 };