The commit adds support to throttle the rate of the RX IRQs to a specified
value. The effect is, that no RX IRQs below the time threshold will fire and
therefore the CPU load gets reduced on the host. Trade-off gaming between
cpu load, throughput, overload.
Modular Sculpt 23.10 on S938 as testcase. In brackets the CPU affinity is
denoted.
ipxe (0,0) -> nic_router (1,0) -> Debian VM vbox6 (3,0) and (3,1)
VM: iperf -C X.X.X.X -t 60 -R
iperf server X.X.X.X is outside Sculpt and sends data due to '-R' to VM
Non representative measure points:
cpu load - ipxe - nic_router - iperf throughput
--------------------------------------------------
w/o patch - ~80% - ~50% - ~706 MBit/s - 0 -> throttling off by default on S938
patch 651 - ~20% - ~35% - ~763 MBit/s - 651 -> 0.166ms throttle RX IRQ
patch 5580 - ~15% - ~25% - ~650 MBit/s - 5580 -> 1.4ms throttle RX IRQ
Issue #5149
