Re: [PATCH] queue stall with blk-mq-sched

On 01/24/2017 05:03 PM, Jens Axboe wrote:

On 01/24/2017 08:54 AM, Hannes Reinecke wrote:

quoted

Hi Jens,

I'm trying to debug a queue stall with your blk-mq-sched branch; with my
latest mpt3sas patches fio stops basically directly after starting a
sequential read :-(

I've debugged things and came up with the attached patch; we need to
restart waiters with blk_mq_tag_idle() after completing a tag.
We're already calling blk_mq_tag_busy() when fetching a tag, so I think
calling blk_mq_tag_idle() is required when retiring a tag.

I'll take a look at this. It sounds like all your grief is related to
shared tag maps, which I don't have anything that uses here. I'll see
if we are leaking it, you should be able to check that by reading the
'active' file in the sysfs directory.

Ah. That'll explain it.

Basically _all_ my HBAs I'm testing with have shared tag maps :-(

Cheers,

Hannes
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Dr. Hannes Reinecke		      zSeries & Storage
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