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tun: enable NAPI for TUN/TAP driver

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Changes TUN driver to use napi_gro_receive() upon receiving packets
rather than netif_rx_ni(). Adds flag IFF_NAPI that enables these
changes and operation is not affected if the flag is disabled.  SKBs
are constructed upon packet arrival and are queued to be processed
later.

The new path was evaluated with a benchmark with the following setup:
Open two tap devices and a receiver thread that reads in a loop for
each device. Start one sender thread and pin all threads to different
CPUs. Send 1M minimum UDP packets to each device and measure sending
time for each of the sending methods:
	napi_gro_receive():	4.90s
	netif_rx_ni():		4.90s
	netif_receive_skb():	7.20s

Signed-off-by: Petar Penkov <peterpenkov96@gmail.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Mahesh Bandewar <maheshb@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Cc: davem@davemloft.net
Cc: ppenkov@stanford.edu
Acked-by: Mahesh Bandewar <maheshb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Petar Penkov
2017-09-22 13:49:14 -07:00
committed by David S. Miller
parent e94cd8113c
commit 943170998b
2 changed files with 119 additions and 15 deletions
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1
include/uapi/linux/if_tun.h
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@@ -60,6 +60,7 @@
/* TUNSETIFF ifr flags */
#define IFF_TUN 0x0001
#define IFF_TAP 0x0002
#define IFF_NAPI 0x0010
#define IFF_NO_PI 0x1000
/* This flag has no real effect */
#define IFF_ONE_QUEUE 0x2000