Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1534411

Re: [PATCH v2] tun: Use netif_receive_skb instead of netif_rx

Show all headers | View raw

From: Andrey Konovalov <andreyknvl@google.com>
Date: Thu,  1 Dec 2016 10:34:40 +0100

> This patch changes tun.c to call netif_receive_skb instead of netif_rx
> when a packet is received (if CONFIG_4KSTACKS is not enabled to avoid
> stack exhaustion). The difference between the two is that netif_rx queues
> the packet into the backlog, and netif_receive_skb proccesses the packet
> in the current context.
> 
> This patch is required for syzkaller [1] to collect coverage from packet
> receive paths, when a packet being received through tun (syzkaller collects
> coverage per process in the process context).
> 
> As mentioned by Eric this change also speeds up tun/tap. As measured by
> Peter it speeds up his closed-loop single-stream tap/OVS benchmark by
> about 23%, from 700k packets/second to 867k packets/second.
> 
> A similar patch was introduced back in 2010 [2, 3], but the author found
> out that the patch doesn't help with the task he had in mind (for cgroups
> to shape network traffic based on the original process) and decided not to
> go further with it. The main concern back then was about possible stack
> exhaustion with 4K stacks.
> 
> [1] https://github.com/google/syzkaller
> 
> [2] https://www.spinics.net/lists/netdev/thrd440.html#130570
> 
> [3] https://www.spinics.net/lists/netdev/msg130570.html
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> ---
> 
> Changes since v1:
> - incorporate Eric's note about speed improvements in commit description
> - use netif_receive_skb CONFIG_4KSTACKS is not enabled

Applied to net-next, thanks!

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH v2] tun: Use netif_receive_skb instead of netif_rx Andrey Konovalov <andreyknvl@google.com> - 2016-12-01 10:40 +0100
  Re: [PATCH v2] tun: Use netif_receive_skb instead of netif_rx Jason Wang <jasowang@redhat.com> - 2016-12-01 10:50 +0100
  Re: [PATCH v2] tun: Use netif_receive_skb instead of netif_rx "Michael S. Tsirkin" <mst@redhat.com> - 2016-12-01 14:10 +0100
  Re: [PATCH v2] tun: Use netif_receive_skb instead of netif_rx David Miller <davem@davemloft.net> - 2016-12-01 20:50 +0100
    Re: [PATCH v2] tun: Use netif_receive_skb instead of netif_rx David Miller <davem@davemloft.net> - 2016-12-07 04:30 +0100
      Re: [PATCH v2] tun: Use netif_receive_skb instead of netif_rx Jason Wang <jasowang@redhat.com> - 2016-12-07 04:50 +0100
    Re: [PATCH v2] tun: Use netif_receive_skb instead of netif_rx Jason Wang <jasowang@redhat.com> - 2016-12-07 04:40 +0100

csiph-web