[openib-general] [PATCH] IB/cma: add rdma_establish

[Michael S. Tsirkin]

Quoting r. Sean Hefty <mshefty at ichips.intel.com>:
> Subject: Re: [PATCH] IB/cma: add rdma_establish
> 
> Michael S. Tsirkin wrote:
> >>>As a side note, reasons for frequent loss of RTU must be investigated.
> >>
> >>A lost RTU shouldn't be any more likely than a lost REQ or REP.  Is the RTU 
> >>never showing up?
> > 
> > 
> > Seems like that. I know fir sure I do accept after REP but remote side never
> > gets ESTABLISHED.
> 
> I looked at the code, then ran some tests.  The REP is retried until an RTU is 
> received, or its number of retries is exhausted.  By modifying the IB CM, I was 
> able to force RTU drops.  Using madeye, I could see that the REP would be 
> retried, resulting in the RTU being resent.  After 4 drops, I had the code 
> receive the RTU, which allowed the test to proceed.
> 
> A couple things to look at in OFED would be the setting of max cm retries and 
> the cm timeout.
> 
> - Sean

OFED uses CMA from upstream kernel. If default parameters there
are inappropriate, maybe should fix them?

BTW, how about the idea of exporting max cm retries in transport-independent
header?

-- 
MST