[ewg] [PATCH] Handling busy responses from the SA

[Mike Heinz]

It's workable, although I really wish there was a way to handle "stupid" apps that aren't written to handle a busy response.

-----Original Message-----
From: Hefty, Sean [mailto:sean.hefty at intel.com] 
Sent: Tuesday, June 08, 2010 12:44 PM
To: Jason Gunthorpe
Cc: Mike Heinz; linux-rdma at vger.kernel.org; ewg at openfabrics.org
Subject: RE: [PATCH] Handling busy responses from the SA

> Also, I guess, it would be a good API choice if the caller could say
> 'get me a reply for this mad or error within 60s' rather than specify
> details like retry counts, etc. The timeout values should be globally
> set and derived from the usual SA provided data for network transits...

I agree with this.  Within the framework of the existing umad ABI, this could be specified by setting the high bit in the ib_user_mad_hdr:timeout_ms field, assuming that no one is using that bit in practice.  The kernel could then freely select the retry/timeout policy for these clients, which for starters could include dropping BUSY responses and adjusting the timeout using an approach similar to what Mike mentioned in a separate email.  Kernel clients could be updated to use this new mode.

Any disagreements to this approach?