[dm-devel] blk-mq request allocation stalls [was: Re: [PATCH v3 0/8] dm: add request-based blk-mq support]

[Jens Axboe]

On 01/09/2015 02:40 PM, Mike Snitzer wrote:
> On Fri, Jan 09 2015 at  4:11pm -0500,
> Jens Axboe <axboe at kernel.dk> wrote:
>
>>
>> Actually, try this one instead, it should be a bit more precise than
>> the first.
>>
>
> Thanks for the test patch.
>
> I'm still seeing failures that look wrong (last_tag=127 could be edge
> condition not handled properly?):
>
> [   14.254632] __bt_get: values before for loop: last_tag=127, index=3
> [   14.255841] __bt_get: values after  for loop: last_tag=64, index=2
> [   14.257036]
> [   14.257036] bt_get: __bt_get() returned -1
> [   14.258051] queue_num=0, nr_tags=128, reserved_tags=0, bits_per_word=5
> [   14.259246] nr_free=128, nr_reserved=0
> [   14.259963] active_queues=0
>
> [  213.115997] __bt_get: values before for loop: last_tag=127, index=3
> [  213.117115] __bt_get: values after  for loop: last_tag=96, index=3
> [  213.118200]
> [  213.118200] bt_get: __bt_get() returned -1
> [  213.121593] queue_num=0, nr_tags=128, reserved_tags=0, bits_per_word=5
> [  213.123960] nr_free=128, nr_reserved=0
> [  213.125880] active_queues=0
>
> [  239.158079] __bt_get: values before for loop: last_tag=8, index=0
> [  239.160363] __bt_get: values after  for loop: last_tag=0, index=0
> [  239.162896]
> [  239.162896] bt_get: __bt_get() returned -1
> [  239.166284] queue_num=0, nr_tags=128, reserved_tags=0, bits_per_word=5
> [  239.168623] nr_free=127, nr_reserved=0
> [  239.170508] active_queues=0

Thanks for testing, can you try this one?

-- 
Jens Axboe

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