Hi Lorenzo, On Thu, Aug 8, 2024, at 12:54 AM, Lorenzo Bianconi wrote: >> Hi Alexander, >> >> On Tue, Jun 28, 2022, at 12:47 PM, Alexander Lobakin wrote: >> > cpumap has its own BH context based on kthread. It has a sane batch >> > size of 8 frames per one cycle. >> > GRO can be used on its own, adjust cpumap calls to the >> > upper stack to use GRO API instead of netif_receive_skb_list() which >> > processes skbs by batches, but doesn't involve GRO layer at all. >> > It is most beneficial when a NIC which frame come from is XDP >> > generic metadata-enabled, but in plenty of tests GRO performs better >> > than listed receiving even given that it has to calculate full frame >> > checksums on CPU. >> > As GRO passes the skbs to the upper stack in the batches of >> > @gro_normal_batch, i.e. 8 by default, and @skb->dev point to the >> > device where the frame comes from, it is enough to disable GRO >> > netdev feature on it to completely restore the original behaviour: >> > untouched frames will be being bulked and passed to the upper stack >> > by 8, as it was with netif_receive_skb_list(). >> > >> > Signed-off-by: Alexander Lobakin <alexandr.lobakin@xxxxxxxxx> >> > --- >> > kernel/bpf/cpumap.c | 43 ++++++++++++++++++++++++++++++++++++++----- >> > 1 file changed, 38 insertions(+), 5 deletions(-) >> > >> >> AFAICT the cpumap + GRO is a good standalone improvement. I think >> cpumap is still missing this. >> >> I have a production use case for this now. We want to do some intelligent >> RX steering and I think GRO would help over list-ified receive in some cases. >> We would prefer steer in HW (and thus get existing GRO support) but not all >> our NICs support it. So we need a software fallback. >> >> Are you still interested in merging the cpumap + GRO patches? > > Hi Daniel and Alex, > > Recently I worked on a PoC to add GRO support to cpumap codebase: > - > https://github.com/LorenzoBianconi/bpf-next/commit/a4b8264d5000ecf016da5a2dd9ac302deaf38b3e > Here I added GRO support to cpumap through gro-cells. > - > https://github.com/LorenzoBianconi/bpf-next/commit/da6cb32a4674aa72401c7414c9a8a0775ef41a55 > Here I added GRO support to cpumap trough napi-threaded APIs (with a > some > changes to them). Cool! > > Please note I have not run any performance tests so far, just verified it does > not crash (I was planning to resume this work soon). Please let me know if it > works for you. I’ll try to run an A/B test on your two approaches as well as Alex’s. I’ve still got some testbeds with production traffic going thru them. Thanks, Daniel
