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? Thanks, Daniel
