On 01/12/2015 09:58 AM, Mike Snitzer wrote:
On Mon, Jan 12 2015 at 11:34am -0500,
Jens Axboe <axboe@xxxxxxxxx> wrote:
On 01/12/2015 09:12 AM, Bart Van Assche wrote:
On 01/12/15 16:42, Jens Axboe wrote:
On 01/12/2015 07:46 AM, Bart Van Assche wrote:
bt_get: __bt_get() returned -1
queue_num=2, nr_tags=62, reserved_tags=0, bits_per_word=3
nr_free=62, nr_reserved=0, may_queue=0
active_queues=8
Can you add dumping of hctx->nr_active when this fails? You case is that
the may_queue logic says no-can-do, so it smells like the nr_active
accounting is wonky since you have supposedly no allocated tags, yet it
clearly thinks that you do.
Hello Jens,
The requested output is as follows:
bt_get: __bt_get() returned -1
queue_num=0, nr_tags=62, reserved_tags=0, bits_per_word=3
nr_free=62, nr_reserved=0, hctx->tags->active_queues=7,
hctx->nr_active=9, hctx_may_queue()=0
active_queues=7
So that does look a bit off, we have (supposedly) 9 active requests,
but nothing allocated. When the mkfs is done and things are idle,
can you try and cat the 'active' file in the mq directory? I want to
see if it drops to zero or stays elevated.
Could this be something flawed in the iSCSI blk-mq implementation? I
haven't ever been able to replicate this problem with virtio-blk.
It's related to a shared tag map, which only happens on scsi-mq. Other
devices generally don't share tag maps.
--
Jens Axboe
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