[openib-general] RFC: detecting duplicate MAD requests

[Michael S. Tsirkin]

Quoting r. Hal Rosenstock <halr at voltaire.com>:
> Subject: Re: RFC: detecting duplicate MAD requests
> 
> On Wed, 2006-06-14 at 17:22, Michael S. Tsirkin wrote:
> > Quoting r. Sean Hefty <mshefty at ichips.intel.com>:
> > > Subject: Re: RFC: detecting duplicate MAD requests
> > > 
> > > Michael S. Tsirkin wrote:
> > > >>We're kind of left with the same issue of trying to determine if a received
> > > >>MAD will generate a response.
> > > > 
> > > > 
> > > > How do you mean? We have IsDS=1 flag for dual-sided, don't we? Dual-sided
> > > > transfer always has a response, doesn't it?
> > 
> > I mean, the flag in the application that says that the transfer is dual-sided.
> > The spec seems to imply that user can figure *from the method* that IsDS=1, so I
> > assume users will have this logic:
> > 
> > "2)
> > Begin the initial transfer by starting the send operation at the point labelled
> > Send. The method or other indication should be interpreted on
> > the other side as initiating a double-sided transfer, causing the receive
> > context to set IsDS=1."
> > 
> > 
> > So why does the MAD layer care whether a received MAD will generate a
> > resonse?  A request arrives - we pass it up. Now the ACK for the direction
> > switch arrives - we pass it up too, application should be waiting for it, it
> > should take the window and pass the response back to us.
> 
> The ACKs are transparent to the application/user.

Well the ACK for the direction switch is special, isn't it?
All I'm saying, let's pass it up to the application.

-- 
MST