[openib-general] openIB question

[john t]

Hi Dotan,

Thanks for your prompt reply. The example that u specified takes address of
data buffer during send and receive and directly copies data into the data
buffer of target machine.

In my case, the target machine has 2 QPs on two different ports. It receives
data from one QP on one port and sends data (same data wihout modification)
through other QP on other port. I want to directly pass the data from one QP
to other QP without storing it locally.

The example code does not seem to support this. It first copies data to a
local buffer (which is not required in my case) and only then it could send
it over other QP. Is there a more efficient way to do this?

regards,
John T


On 8/16/06, Dotan Barak <dotanb at mellanox.co.il> wrote:
>
> Hi and welcome John
> :)
>
> On Wednesday 16 August 2006 09:01, john t wrote:
> > Hi,
> >
> > I am new to openIB and have some questions.
> >
> > - A QP has two work queues, send work queue and receive work queue. When
> > host A sends a data buffer to host B using a QP (RC), I want to know if
> data
> > is copied into the send work queue of host A and then into the receive
> work
> > queue of host B or is it only the address of data buffer that is pushed
> into
> > the send work q and receive work q.
> If you use RC QP and send the data using the SEND opcode, if you'll get a
> completion
> (with good status) in the sender, that means that the data was written in
> the receiver buffer.
> >
> > - I want to develop an application (using uverbs or any such appropriate
> > tool) that uses raw datagrams. Basically I want to send an IB packet
> from
> > host A to host B and receive the entire IB packet (along with headers +
> > data) at host B. Is such a thing supported in openIB? Is there any
> example
> > which I can look at?
> In IB, you won't see the various headers (expect in UD QPs, in which you
> will get the GRH).
>
> You can look at the example in the following url:
>
> https://openib.org/svn/gen2/trunk/src/userspace/libibverbs/examples/rc_pingpong.c
>
> > regards,
> > John T
> >
>
>
> Dotan
>
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