lkml.org 
[lkml]   [2015]   [Nov]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [patch, v3] blk-mq: avoid excessive boot delays with large lun counts
From
Date
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



\
 
 \ /
  Last update: 2015-11-03 17:21    [W:1.516 / U:0.200 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site