Messages in this thread | | | Subject | Re: [patch, v3] blk-mq: avoid excessive boot delays with large lun counts | From | Jens Axboe <> | Date | Tue, 3 Nov 2015 08:46:04 -0700 |
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On 11/03/2015 08:40 AM, Jeff Moyer wrote: > Hi, > > Zhangqing Luo reported long boot times on a system with thousands of > LUNs when scsi-mq was enabled. He narrowed the problem down to > blk_mq_add_queue_tag_set, where every queue is frozen in order to set > the BLK_MQ_F_TAG_SHARED flag. Each added device will freeze all queues > added before it in sequence, which involves waiting for an RCU grace > period for each one. We don't need to do this. After the second queue > is added, only new queues need to be initialized with the shared tag. > We can do that by percolating the flag up to the blk_mq_tag_set, and > updating the newly added queue's hctxs if the flag is set. > > This problem was introduced by commit 0d2602ca30e41 (blk-mq: improve > support for shared tags maps).
Applied, thanks Jeff and Ming.
-- Jens Axboe
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