From 0d2602ca30e410e84e8bdf05c84ed5688e0a5a44 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 13 May 2014 15:10:52 -0600 Subject: 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 --- block/blk-timeout.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) (limited to 'block/blk-timeout.c') diff --git a/block/blk-timeout.c b/block/blk-timeout.c index 448745683d28..43e8b515806f 100644 --- a/block/blk-timeout.c +++ b/block/blk-timeout.c @@ -166,6 +166,17 @@ void blk_abort_request(struct request *req) } EXPORT_SYMBOL_GPL(blk_abort_request); +unsigned long blk_rq_timeout(unsigned long timeout) +{ + unsigned long maxt; + + maxt = round_jiffies_up(jiffies + BLK_MAX_TIMEOUT); + if (time_after(timeout, maxt)) + timeout = maxt; + + return timeout; +} + /** * blk_add_timer - Start timeout timer for a single request * @req: request that is about to start running. @@ -200,7 +211,7 @@ void blk_add_timer(struct request *req) * than an existing one, modify the timer. Round up to next nearest * second. */ - expiry = round_jiffies_up(req->deadline); + expiry = blk_rq_timeout(round_jiffies_up(req->deadline)); if (!timer_pending(&q->timeout) || time_before(expiry, q->timeout.expires)) { -- cgit