Instead of blocking BH in whole sk_busy_loop(), block them
only around ->ndo_busy_poll() calls.
This has many benefits.
1) allow tunneled traffic to use busy poll as well as native traffic.
Tunnels handlers usually call netif_rx() and depend on net_rx_action()
being run (from sofirq handler)
2) allow RFS/RPS being used (sending IPI to other cpus if needed)
3) use the 'lets burn cpu cycles' budget to do useful work
(like TX completions, timers, RCU callbacks...)
4) reduce BH latencies, making busy poll a better citizen.
Tested:
Tested with SIT tunnel
lpaa5:~# echo 0 >/proc/sys/net/core/busy_read
lpaa5:~# ./netperf -H 2002:af6:786::1 -t TCP_RR
MIGRATED TCP REQUEST/RESPONSE TEST from ::0 (::) port 0 AF_INET6 to 2002:af6:786::1 () port 0 AF_INET6 : first burst 0
Local /Remote
Socket Size Request Resp. Elapsed Trans.
Send Recv Size Size Time Rate
bytes Bytes bytes bytes secs. per sec
lpaa5:~# ./netperf -H 2002:af6:786::1 -t TCP_RR
MIGRATED TCP REQUEST/RESPONSE TEST from ::0 (::) port 0 AF_INET6 to 2002:af6:786::1 () port 0 AF_INET6 : first burst 0
Local /Remote
Socket Size Request Resp. Elapsed Trans.
Send Recv Size Size Time Rate
bytes Bytes bytes bytes secs. per sec
16384 87380 1 1 10.00 58314.77
16384 87380
Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>