NAME

       ibv_modify_qp_rate_limit - modify the send rate limits attributes of a queue pair (QP)

SYNOPSIS

       #include <infiniband/verbs.h>

       int ibv_modify_qp_rate_limit(struct ibv_qp *qp, struct ibv_qp_rate_limit_attr *attr);

DESCRIPTION

       ibv_modify_qp_rate_limit()  modifies  the  send  rate limiting packet pacing attributes of QP qp with the
       attributes  in  attr.   The  argument  attr  is  an  ibv_qp_rate_limit_attr   struct,   as   defined   in
       <infiniband/verbs.h>.

       The  rate_limit  defines the MAX send rate this QP will send as long as the link in not blocked and there
       are work requests in send queue.

       Finer control for shaping the rate limit of a QP is achieved by defining the max_burst_sz,  single  burst
       max  bytes  size  and the typical_pkt_sz, typical packet bytes size. These allow the device to adjust the
       inter-burst gap delay required to correctly shape the scheduling of sends to the wire in order  to  reach
       for requested application requirements.

       Setting  a  value  of 0 for max_burst_sz or typical_pkt_sz will use the devices defaults.  typical_pkt_sz
       will default to the port's MTU value.

       struct ibv_qp_rate_limit_attr {
               uint32_t        rate_limit;     /* kbps */
               uint32_t        max_burst_sz;   /* bytes */
               uint16_t        typical_pkt_sz; /* bytes */
       };

RETURN VALUE

       ibv_modify_qp_rate_limit() returns 0 on success, or the value of errno on failure  (which  indicates  the
       failure reason).

ERRORS

   EINVAL
       Invalid arguments.

   EOPNOTSUPP
       Function  is  not  implemented  for  this  device.   (ENOSYS may sometimes be returned by old versions of
       libibverbs).

SEE ALSO

       ibv_create_qp(3), ibv_destroy_qp(3), ibv_modify_qp(3), ibv_query_qp(3)

AUTHORS

       Alex Rosenbaum <alexr@mellanox.com>

       Bodong Wang <bodong@mellanox.com>