Comparison of Onloading and Offloading Strategies to Improve Network Interfaces

This paper compares the onloading and offloading alternatives for improving up communication. Both strategies try to release host CPU cycles by taking advantage of the execution of the communication workload in other processors present in the node. Nevertheless, whereas onloading uses another general-purpose processor, either included in a chip multiprocessor (CMP) or in a symmetric multiprocessor (SMP), offloading takes advantage of processors in programmable network interface cards (NICs). Here, it is shown that the relative improvement on peak throughput offered by offloading and onloading depends on the rate of application workload to communication overhead, the message sizes, and the characteristics of system architecture, more specifically the buses bandwidth and the way the NIC is connected to the system processor and memory. In our implementations, offloading provides lower latencies than onloading although the CPU utilization and interrupts are lower for onloading.