Re: dumping queue state

[Bart Van Assche <Bart.VanAssche-Sjgp3cTcYWE@public.gmane.org>]

On Wed, 2017-12-20 at 09:53 -0600, Steve Wise wrote:
> I have a need to provide tools for customers to gather runtime state for an
> rdma device.   Say, when an application is stuck waiting for some completion
> or other rdma event.   This includes hw/fw state of course, and equally as
> important, rdma object sw state.  Is debugfs the correct way to export this
> sw state?  The data is quite large potentially; each QP, its structures, the
> dma queue memory, etc.  Ditto for CQs.  Also MR state, etc etc.  It seems
> that would be overloading debugfs to me.  Currently the hw/fw state is being
> gathered via ethtool dump commands (--get-dump, --register-dump,
> --eeprom-dump).  I am considering using the ethtool --get-dump method for
> the low level driver to also include dumping the rdma queue state for the
> device.   Is that a reasonable approach?
> 
> Any thoughts/suggestions? 

Hello Steve,

I'm not sure what the best solution is for RDMA queues. But if you want you can
have a look at block/blk-mq-debugfs.c. That code has been added recently and has
been very valuable for debugging block layer / SCSI queue lockups.

Bart.