Hi All, Sorry for asking this question as this might sound very fundamental. I am very much new in rdma and Linux. I am trying to figure out how fast memory registration improves the cost of registration compared to normal registration ?. As per my understanding when we do memory registration then following steps occur. 1. The pages are pinned in physical memory 2. The physical addresses are transferred to the RNIC via bus specific mechanism to which RNIC is connected, in my case it is PCIe. Once a memory is registered we can acquire Lkey and Rkey. This is the case with normal registration. As mentioned in the paper named An Efficient Design for Fast Memory Registration in RDMA "With FMR, user pre-allocates a table in kernel memory to record physical address of memory region, and pre writes I/O registers of RDMA card to register memory information, and only fills the table for physical address of memory region during the real memory registration operations." So my question is in case of fast registration when exactly physical addresses are written in registers of RNIC card. If it is done in initialization as I am thinking by reading this statement, in that case the physical location of data buffer to be registered may be different with the address that has been programmed to the RNIC. I have read in RDMA verbs specification that in case of fast registration we need to create a work request and post to SQ. Why this kind of approach is needed in case of fast registration. Some clarification of this will be highly appreciated. Regards, Arka -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
