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udp: avoid one cache line miss in recvmsg() 

UDP_SKB_CB(skb)->partial_cov is located at offset 66 in skb,
requesting a cold cache line being read in cpu cache.

We can avoid this cache line miss for UDP sockets,
as partial_cov has a meaning only for UDPLite.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2016-11-18 17:18:03 -08:00 committed by David S. Miller
parent ee9d5461c0
commit d21dbdfe0a
2 changed files with 4 additions and 2 deletions
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3
net/ipv4/udp.c
View File

@ -1389,7 +1389,8 @@ try_again:
* coverage checksum (UDP-Lite), do it before the copy.
*/
if (copied < ulen || UDP_SKB_CB(skb)->partial_cov || peeking) {
if (copied < ulen || peeking ||
(is_udplite && UDP_SKB_CB(skb)->partial_cov)) {
checksum_valid = !udp_lib_checksum_complete(skb);
if (!checksum_valid)
goto csum_copy_err;

3
net/ipv6/udp.c
View File

@ -363,7 +363,8 @@ try_again:
* coverage checksum (UDP-Lite), do it before the copy.
*/
if (copied < ulen || UDP_SKB_CB(skb)->partial_cov || peeking) {
if (copied < ulen || peeking ||
(is_udplite && UDP_SKB_CB(skb)->partial_cov)) {
checksum_valid = !udp_lib_checksum_complete(skb);
if (!checksum_valid)
goto csum_copy_err;