[openib-general] Send_bw in UD

[Michael S. Tsirkin]

> Quoting r. Chevchenkovic Chevchenkovic <chevchenkovic at gmail.com>:
> Subject: Send_bw in UD
> 
> Hi,
>   Infiniband specification says that the completion notification in case of RC
> occurs when the data has actually reached the destination buffer. Whereas for
> UD it is given when the data is placed on the infiniband line.
> I was going through the code send_bw.c( https://openfabrics.org/svn/gen2/
> tags/openib-1.0-rc1/src/userspace/perftest/send_bw.c  ).  This tells the time
> taken for the data to reach the destination.

No, this test measures streaming bandwidth. Compare this to UDP bandwidth test.

> In the case of UD the same code is used. Should it not have the code which
> waits for the acknowledgement from the destination?

Once, at the end of the test? I believe the difference will be negligeable,
and the test will get more confusing.

>     Alternately, is the bandwidth computation wrong in this case? 
>  Comments will be welcome,

The computation is performed correctly. The test currently will simply block
forever on server side if there is some packet loss.  If the test run to completion,
no packets were lost and this means that streaming bandwidth was
measured correctly.
 
-- 
MST