Re: [net-next PATCH 2/5] net: Call sk_mark_napi_id() in the ACK receive path

On Thu, Mar 16, 2017 at 3:04 PM, Eric Dumazet [off-list ref] wrote:

On Thu, 2017-03-16 at 11:32 -0700, Alexander Duyck wrote:

quoted

From: Sridhar Samudrala <sridhar.samudrala@intel.com>

Call sk_mark_napi_id() in the ACK receive path of a TCP_NEW_SYN_RECV
socket, so that sk->napi_id is set even if the socket hasn't yet received
any data.  With this change we should be able to start busy polling
slightly earlier.

Signed-off-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
Signed-off-by: Alexander Duyck <redacted>
---
 net/ipv4/tcp_ipv4.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 08d870e45658..b86002a296f1 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c

@@ -1687,6 +1687,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
                      tcp_v4_send_reset(nsk, skb);
                      goto discard_and_relse;
              } else {
+                     sk_mark_napi_id(nsk, skb);
                      sock_put(sk);
                      return 0;
              }

Seems good, but what about IPv6 ?

Sorry, I spaced out and overlooked that this would also be an issue for IPv6.

Frankly this calls for the sk_mark_napi_id() being done in
tcp_child_process() instead of its four callers.

We can look into that for the next version.