The generally accepted rule of thumb is that 1bps of network
link requires 1Hz of CPU processing. Figures 11, 12
give a full story of this rule of thumb. (where Hz/bps ratio
= %CPU utilization * processor speed / bandwidth). It had
held up remarkably well over the years, albeit only for bulk
data transfer at large sizes. For smaller transfers, we found
the processing requirement to be 6-7 times as expected.
Moreover, the figures show that network processing is not
scaling with CPU speeds. The processing needs per byte
increase when going from 800MHz to 2.4GHz. This happens
because as CPU speed increases, the disparity between
memory and I/O latencies versus CPU speeds intensifies.
Does anyone know if memory latency is still causing problems in common implementations (like linux and freebsd)? I would think that the parts that are the bottleneck could be re-written with that in mind and gain quite a bit from it.
The generally accepted rule of thumb is that 1bps of network link requires 1Hz of CPU processing. Figures 11, 12 give a full story of this rule of thumb. (where Hz/bps ratio = %CPU utilization * processor speed / bandwidth). It had held up remarkably well over the years, albeit only for bulk data transfer at large sizes. For smaller transfers, we found the processing requirement to be 6-7 times as expected. Moreover, the figures show that network processing is not scaling with CPU speeds. The processing needs per byte increase when going from 800MHz to 2.4GHz. This happens because as CPU speed increases, the disparity between memory and I/O latencies versus CPU speeds intensifies.