questions about the memory bandwidth
Posted: Thu Nov 27, 2014 5:50 amHi all,
I tried to measure the Epiphany's data communication performance with my board, and found that the read bandwidth of epi_core-to-eRAM are not like i expected. I tested it with variable size data fetching, but the bandwidth never exceed 100MB/s. It fails to reach the claimed GB-level peak bandwidth of e-link, or that of the HP AXI port in Zynq end.
I guess the problem may be sourced to the emesh protocol that doesnt seem to support data burst request. The DMA or read request is decomposed into segmented emesh requests, so that the AXI slave port has to forward the decomposed burst reads and get responded by the dram memory for multiple times. If this is the case, the burst transmission mode of AXI cannot be exploited for bulk data read. So, if i want to solve the issue, Is it possible to do something with Zynq's PL to change the glue logics between e-link and AXI ports?
since I'm fresh to parallela, please correct me if i'm wrong.
Thank you.
FYI, I clip the measurement results in thread.
I tried to measure the Epiphany's data communication performance with my board, and found that the read bandwidth of epi_core-to-eRAM are not like i expected. I tested it with variable size data fetching, but the bandwidth never exceed 100MB/s. It fails to reach the claimed GB-level peak bandwidth of e-link, or that of the HP AXI port in Zynq end.
I guess the problem may be sourced to the emesh protocol that doesnt seem to support data burst request. The DMA or read request is decomposed into segmented emesh requests, so that the AXI slave port has to forward the decomposed burst reads and get responded by the dram memory for multiple times. If this is the case, the burst transmission mode of AXI cannot be exploited for bulk data read. So, if i want to solve the issue, Is it possible to do something with Zynq's PL to change the glue logics between e-link and AXI ports?
since I'm fresh to parallela, please correct me if i'm wrong.
Thank you.
FYI, I clip the measurement results in thread.
- bandwidth (1)_页面_2.jpg (75.78 KiB) Viewed 7583 times
- bandwidth (1)_页面_1.jpg (59.55 KiB) Viewed 7583 times