Måns Rullgård <[email protected]> writes: > David Miller <[email protected]> writes: > >> From: Måns Rullgård <[email protected]> >> Date: Wed, 11 Nov 2015 00:40:09 +0000 >> >>> When the DMA complete interrupt arrives, the next chain should be >>> kicked off as quickly as possible, and I don't see why that would >>> benefit from being done in napi context. >> >> NAPI isn't about low latency, it's about fairness and interrupt >> mitigation. >> >> You probably don't even realize that all of the TX SKB freeing you do >> in the hardware interrupt handler end up being actually processed by a >> scheduled software interrupt anyways. >> >> So you are gaining almost nothing by not doing TX completion in NAPI >> context, whereas by doing so you would be gaining a lot including >> more simplified locking or even the ability to do no locking at all. > > TX completion is separate from restarting the DMA, and moving that to > NAPI may well be a good idea. Should I simply napi_schedule() if the > hardware indicates TX is complete and do the cleanup in the NAPI poll > function?
I tried that, and throughput (as measured by iperf3) dropped by 2%. Maybe I did something wrong. -- Måns Rullgård [email protected] -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
