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authorEric Dumazet <edumazet@google.com>2015-10-09 05:33:22 +0300
committerDavid S. Miller <davem@davemloft.net>2015-10-13 05:28:22 +0300
commit8e5eb54d303b7cb1174977ca79030e135728c95e (patch)
tree9aebc1d9e60ccbb559dac5d0d8d11f41b95df3c2 /include/net/request_sock.h
parent70da268b569d32a9fddeea85dc18043de9d89f89 (diff)
downloadlinux-8e5eb54d303b7cb1174977ca79030e135728c95e.tar.xz
net: align sk_refcnt on 128 bytes boundary
sk->sk_refcnt is dirtied for every TCP/UDP incoming packet. This is a performance issue if multiple cpus hit a common socket, or multiple sockets are chained due to SO_REUSEPORT. By moving sk_refcnt 8 bytes further, first 128 bytes of sockets are mostly read. As they contain the lookup keys, this has a considerable performance impact, as cpus can cache them. These 8 bytes are not wasted, we use them as a place holder for various fields, depending on the socket type. Tested: SYN flood hitting a 16 RX queues NIC. TCP listener using 16 sockets and SO_REUSEPORT and SO_INCOMING_CPU for proper siloing. Could process 6.0 Mpps SYN instead of 4.2 Mpps Kernel profile looked like : 11.68% [kernel] [k] sha_transform 6.51% [kernel] [k] __inet_lookup_listener 5.07% [kernel] [k] __inet_lookup_established 4.15% [kernel] [k] memcpy_erms 3.46% [kernel] [k] ipt_do_table 2.74% [kernel] [k] fib_table_lookup 2.54% [kernel] [k] tcp_make_synack 2.34% [kernel] [k] tcp_conn_request 2.05% [kernel] [k] __netif_receive_skb_core 2.03% [kernel] [k] kmem_cache_alloc Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/request_sock.h')
-rw-r--r--include/net/request_sock.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/net/request_sock.h b/include/net/request_sock.h
index 95ab5d7aab96..6b818b77d5e5 100644
--- a/include/net/request_sock.h
+++ b/include/net/request_sock.h
@@ -50,9 +50,9 @@ struct request_sock {
struct sock_common __req_common;
#define rsk_refcnt __req_common.skc_refcnt
#define rsk_hash __req_common.skc_hash
+#define rsk_listener __req_common.skc_listener
struct request_sock *dl_next;
- struct sock *rsk_listener;
u16 mss;
u8 num_retrans; /* number of retransmits */
u8 cookie_ts:1; /* syncookie: encode tcpopts in timestamp */