[openib-general] [PATCH 1/2] perftest: enhancement to rdma_bw to allow use of RDMA CM

[Pradipta Kumar Banerjee]

Steve Wise wrote:
> On Wed, 2006-07-05 at 14:29 +0300, Michael S. Tsirkin wrote:
>> Thanks for following up on this, on the surface looks good.
>> I'm busy at the moment, but a quick question:
>>
>> Quoting r. Pradipta Kumar Banerjee <bpradip at in.ibm.com>:
>>> +static void pp_wait_for_done(struct pingpong_context *ctx)
>>> +{
>>> +	struct ibv_wc wc;
>>> +	int ne;
>>> +
>>> +	do {
>>> +		usleep(500);
>>> +		ne = ibv_poll_cq(ctx->rcq, 1, &wc);
>>> +	} while (ne == 0);
>> I wander whether we can get rid of the rcq and an extra send at the
>> end by simply closing the QP, and ignoring the possible completion with error
>> for the last round. I think this would be a nice simplification.
>> What do you think?
>>
> 
> For IWARP, the ULP must quiesce the QP before moving it to CLOSING (ie
> before doing an rdma_disconnect()).  By quiesce, I mean make sure there
> are no outstanding SQ WRs and no outstanding RDMA reads in progress.
> That's why there is this message exchange at the end of the test.  
> 
> For instance, in the bi-directional bandwidth tests, one side could
> finish the test and issue an rdma_disconnect() while the other end still
> has pending rdma writes.  This is an error condition in iWARP.  So they
> sync up at the end with a message exchange before disconnecting.
> 
> Make sense?
Steve,
  Is it necessary to handle this error condition for measuring bandwidth ?
Once the bandwidth computation is done, let the application terminate, which 
should anyway flush the queues.

Thanks,
Pradipta Kumar.

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