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authorJens Axboe <axboe@fb.com>2014-05-14 01:10:52 +0400
committerJens Axboe <axboe@fb.com>2014-05-14 01:10:52 +0400
commit0d2602ca30e410e84e8bdf05c84ed5688e0a5a44 (patch)
treea456339b9271a400a63aa6defddc85d3eebb95f8 /include/linux/blkdev.h
parent1f236ab22ce3bc5d4f975aa116966c0ea7ec2013 (diff)
downloadlinux-0d2602ca30e410e84e8bdf05c84ed5688e0a5a44.tar.xz
blk-mq: improve support for shared tags maps
This adds support for active queue tracking, meaning that the blk-mq tagging maintains a count of active users of a tag set. This allows us to maintain a notion of fairness between users, so that we can distribute the tag depth evenly without starving some users while allowing others to try unfair deep queues. If sharing of a tag set is detected, each hardware queue will track the depth of its own queue. And if this exceeds the total depth divided by the number of active queues, the user is actively throttled down. The active queue count is done lazily to avoid bouncing that data between submitter and completer. Each hardware queue gets marked active when it allocates its first tag, and gets marked inactive when 1) the last tag is cleared, and 2) the queue timeout grace period has passed. Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'include/linux/blkdev.h')
-rw-r--r--include/linux/blkdev.h3
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 94b27210641b..6bc011a09e82 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -481,6 +481,9 @@ struct request_queue {
wait_queue_head_t mq_freeze_wq;
struct percpu_counter mq_usage_counter;
struct list_head all_q_node;
+
+ struct blk_mq_tag_set *tag_set;
+ struct list_head tag_set_list;
};
#define QUEUE_FLAG_QUEUED 1 /* uses generic tag queueing */