[ofa-general] Re: [PATCHv2] IB/mad: fix duplicated kernel thread name

[Sean Hefty]

> Can you explain why would not the IB CM use the thread context provided 
> by the mad layer?

You can end up with deadlock conditions when destroying cm_id's that 
have outstanding MADs.  It also increases MAD processing time, which can 
increase dropping MADs.

> Second, if the CM needs a different context why not use the system 
> threads? I understood from Michael's reply that the CM code relies on 
> some thread/queue flushing at the time of CM ID destruction, is it an 
> implementation issue that can change? if not, can't one dedicated thread 
> do the job?

The timing and use of the system threads is unknown.  When the ib_mad 
module was created, it was suggested that the system threads not be 
used.  (I think it was Roland who recommended this.)  We can change to 
system threads, but it does open the possibility of complicated deadlock 
conditions if other modules use the system threads as well.

The CM could change to using a single dedicated thread, but if there are 
multiple processors available, why restrict processing to only being 
able to use one of them?

- Sean