[openib-general] Mellanox HCAs: outstanding RDMAs

[Manpreet Singh]

We have seen this happen over an IB analyzer. Recompiling the mthca driver
with a high value like 64 or 128 works around this problem.
When the condition hits, the HCA receiving the 4+ RDMAs generates an invalid
request error.

Any ideas as to when this patch might enter the mainline sources?

Thanks,
 Manpreet.


On 6/2/06, Roland Dreier <rdreier at cisco.com> wrote:
>
>     Manpreet> Mellanox HCA can handle has been configured at 4
>     Manpreet> (mthca_main.c: default_profile: rdb_per_qp). And the
>     Manpreet> HCAs can support a much higher value (128 I think).
>
>     Manpreet> Could we move this value higher or atleast make it
>     Manpreet> configurable?
>
> Leonid Arsh has a patch that I will integrate soon that makes this
> configurable.
>
> However, I'm curious.  Do you have a workload where this actually
> makes a measurable difference?  It seems that having 4 RDMA requests
> outstanding on the wire should be enough to get things to pipeline
> pretty well.
>
> If you haven't tested this, right now you can of course edit
> mthca_main.c to change the default value and recompile.
>
> - R.
>
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