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authorBart Van Assche <bart.vanassche@wdc.com>2018-01-10 08:33:33 -0800
committerJens Axboe <axboe@kernel.dk>2018-01-10 09:45:29 -0700
commitfcd36c36f381f534adad5a6c6485db4405d5ea42 (patch)
tree1f97dc35dc4382215a15a5112fc559b1b5dd7f2d /block
parent5f15684bd5e5ef39d4337988864fec8012471dda (diff)
blk-mq: Explain when 'active_queues' is decremented
It is nontrivial to derive from the blk-mq source code when blk_mq_tags.active_queues is decremented. Hence add a comment that explains this. Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Hannes Reinecke <hare@suse.de> Cc: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r--block/blk-mq.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 9aa24c9508f9..266fc4f6b046 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -954,6 +954,12 @@ static void blk_mq_timeout_work(struct work_struct *work)
data.next = blk_rq_timeout(round_jiffies_up(data.next));
mod_timer(&q->timeout, data.next);
} else {
+ /*
+ * Request timeouts are handled as a forward rolling timer. If
+ * we end up here it means that no requests are pending and
+ * also that no request has been pending for a while. Mark
+ * each hctx as idle.
+ */
queue_for_each_hw_ctx(q, hctx, i) {
/* the hctx may be unmapped, so check it here */
if (blk_mq_hw_queue_mapped(hctx))

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