On Wed, Nov 11, 2015 at 11:25:06AM +0200, Sagi Grimberg wrote: > For RDMA READs, a HCA will perform the memory scatters when on the RX > path, when receiving the read responses containing the data. This means > that the HCA needs to perform a lookup of the relevant scatter entries > upon each read response. Due to that, modern HCAs keep a dedicate cache > for this type of RX-path lookup (which is limited in size naturally).
There is always a memory scatter, and MR setup overheads and table reads are not zero. There is nothing architectural in the verbs or IBA that would require a HCA to run slower for SGL than MR... As you say, another choice the ULP should not be making.. Even selecting the optimal SGL list len is not something the ULP should do, in that case. Jason -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
