[ofa-general] [PATCH 3/4] rdma/cm: add ability to specify typeof service

[Eitan Zahavi]

Hi Sean,

The point is that the SID and QoS Class (ala DiffServ class coming from
TOS) are written to different fields of the QoS aware PR:
* SID is written into the PR new SID field.
* The QoS Class coming from the socket option gets into the QoSClass
field.

To select the QoS level the policy on the SM/SA might use both fields,
one of the fields or none of the fields.
But this is what policy is all about.

Eitan Zahavi

> -----Original Message-----
> From: Sean Hefty [mailto:mshefty at ichips.intel.com] 
> Sent: Wednesday, August 08, 2007 9:52 PM
> To: Or Gerlitz
> Cc: Eitan Zahavi; OpenIB
> Subject: Re: [ofa-general] [PATCH 3/4] rdma/cm: add ability 
> to specify typeof service
> 
> > To mimic sockets, rdma_set_service_type() is perfectly correct and 
> > usable by socket offloaders such as SDP and RDS, so they 
> can translate 
> > an IP_TOS setsockopt() call to rdma_set_service_type(). 
> This plugs to 
> > the case where the application wants to request per 
> connection QoS class.
> 
> Adding the SID to the PR query is easy enough to do.  Here's 
> the issue that I would like to resolve first.
> 
> Starting first with something transport neutral, I propose the using
> rdma_set_service_type() combined with the flowinfo in the 
> IPv6 address. 
>   If we can agree that this is usable, now let's add the SID 
> to the PR query.
> 
> Since, SID -> QoS, and rdma_set_service_type() sets the QoS, 
> what gets set in the PR query?  The SID -> QoS may not match 
> the QoS requested by the application.  Should the SID always 
> be set, or only if QoS is not specified through some other means?
> 
> - Sean
>