On Wednesday 29 August 2007 10:15, James Chapman wrote: > Jan-Bernd Themann wrote: > > What I'm trying to improve with this approach is interrupt > > mitigation for NICs where the hardware support for interrupt > > mitigation is limited. I'm not trying to improve this for NICs > > that work well with the means their HW provides. I'm aware of > > the fact that this scheme has it's tradeoffs and certainly > > can not be as good as a HW approach. > > So I'm grateful for any ideas that do have less tradeoffs and > > provide a mechanism to reduce interrupts without depending on > > HW support of the NIC. > > > > In the end I want to reduce the CPU utilization. And one way > > to do that is LRO which also works only well if there are more > > then just a very few packets to aggregate. So at least our > > driver (eHEA) would benefit from a mix of timer based polling > > and plain NAPI (depending on load situations). > > Wouldn't you achieve the same result by enabling hardware interrupt > mitigation in eHEA in combination with NAPI? Presumably a 10G interface > has hardware mitigation features?
Quote from above: "What I'm trying to improve with this approach is interrupt mitigation for NICs where the hardware support for interrupt mitigation is limited" So guess why I'm doing that ;-) > > > If there is no need for a generic mechanism for this kind of > > network adapters, then we can just leave this to each device > > driver. > > I've been looking at this from a different angle. My goal is to optimize > NAPI packet forwarding rates while minimizing packet latency. Using > hardware interrupt mitigation hurts latency so I'm investigating ways to > turn it off without risking NAPI poll on/off thrashing at certain packet > rates. > > Jan-Bernd, I think I've found a solution to the issue that you > highlighted with my scheme yesterday and it doesn't involve generating > other interrupts using hrtimers etc. :) Initial results are very > encouraging in my setups. Would you be willing to test it with eHEA? I > don't have a 10G setup. If results are encouraging, I'll post an RFC to > ask for review / feedback from the NAPI experts here. What do you think? > I'm not sure which solution you mean. If you post your RFC, please create a new thread (other title) _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
