CODEWITHSUNDEEP
bandwidthpci-enicinfinibandrdma
Dillion Wang
Dillion Wang

Reputation: 361

How to dynamically modify QP rate limit in ConnectX-6 Infiniband/VPI adapter

I have a ConnectX-6 Infiniband/VPI Adapter. I can setup the hardware rate limit when creating a qp like this:

...
ibv_qp_attr.ah_attr.static_rate = 7; // set qp rate limit to 40Gbps
...
ibv_modify_qp(qp, &ibv_qp_attr, flags); 
...

But I cannot dynamically change the qp rate limit later using the above code after creating the qp.

I also checked the ibv_modify_qp_rate_limit() API, but it keeps return EINVAL when I try to set the rate limit using this API:

struct ibv_qp_rate_limit_attr rl_attr;
memset(&rl_attr, 0, sizeof(rl_attr));
rl_attr.rate_limit = 100;
ibv_modify_qp_rate_limit(qp, &rl_attr); // returns EINVAL

Am I using the API right? How can I dynamically change the hardware rate limit of a qp? (or set the global hardware rate limit).

Upvotes: 1

Views: 481

Answers (1)

Roland
Roland

Reputation: 6583

The rate_limit attribute is in Kbps. I suspect 100 Kbps is too low a limit for the device to handle (the original static_rate interface can only go down to 1X single data rate, which is 2.5 Gbps). You can check by using the

ibv_query_device_ex(context, &device_attr)

API and making sure your requested rate limit is between

device_attr.packet_pacing_caps.qp_rate_limit_min

and

device_attr.packet_pacing_caps.qp_rate_limit_max

Upvotes: 0

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