On Fri, Jun 12, 2026 at 2:40 AM Maciej Fijalkowski <[email protected]> wrote: > > On Thu, Jun 11, 2026 at 03:12:39PM +0800, [email protected] wrote: > > From: Menglong Dong <[email protected]> > > > > For now, we use sk_busy_loop() in __xsk_sendmsg() to send the data in tx > > ring. The sk_busy_loop() will poll on the target NAPI. However, for the > > nic driver that support the tx napi, such as virtio-net, it can't schedule > > the tx NAPI, but only the rx NAPI. If we enable the busy_poll for xsk and > > use virtio-net, we can't send data, as the rx NAPI in virtio-net doesn't > > handle the packet sending. > > Am I reading this right that you decided to break busy-poll support for > zero-copy drivers that happen to handle transmit side from Rx NAPI context > in favor of supporting virtio-net?
Oh, nop. This series only has an impact for virtio-net. For the other driver, the logic doesn't change. I added a "tx_napi" field to struct nap_struct. For now, only virtio-net will initialize it, as only virtio-net has the "tx napi". In __napi_busy_loop(), we will use the napi->tx_napi, if it is not NULL and we are in the tx code path(sk_tx_busy_loop), instead of napi. Thanks! Menglong Dong > > > > > Fix this by introduce the sk_tx_busy_loop(), which will poll on the tx > > NAPI if available. To get the tx NAPI from the napi_id, we add the > > "tx_napi" field to napi_struct, which is ugly :/ > > > > Another choice is to call virtnet_xsk_xmit() in virtnet_poll() too. But > > this a little contradict the design of tx NAPI. > > > > Menglong Dong (3): > > net: busy-poll: introduce sk_tx_busy_loop() > > virtio_net: initialize napi.tx_napi in virtnet_alloc_queues() > > xsk: replace sk_busy_loop with sk_tx_busy_loop in __xsk_sendmsg() > > > > drivers/net/virtio_net.c | 1 + > > include/linux/netdevice.h | 1 + > > include/net/busy_poll.h | 41 ++++++++++++++++++++++++++++++++++++--- > > net/core/dev.c | 23 +++++----------------- > > net/xdp/xsk.c | 2 +- > > 5 files changed, 46 insertions(+), 22 deletions(-) > > > > -- > > 2.54.0 > >
