openvswitch: Compact sw_flow_key.
Minimize padding in sw_flow_key and move 'tp' top the main struct.
These changes simplify code when accessing the transport port numbers
and the tcp flags, and makes the sw_flow_key 8 bytes smaller on 64-bit
systems (128->120 bytes). These changes also make the keys for IPv4
packets to fit in one cache line.
There is a valid concern for safety of packing the struct
ovs_key_ipv4_tunnel, as it would be possible to take the address of
the tun_id member as a __be64 * which could result in unaligned access
in some systems. However:
- sw_flow_key itself is 64-bit aligned, so the tun_id within is
always
64-bit aligned.
- We never make arrays of ovs_key_ipv4_tunnel (which would force
every
second tun_key to be misaligned).
- We never take the address of the tun_id in to a __be64 *.
- Whereever we use struct ovs_key_ipv4_tunnel outside the
sw_flow_key,
it is in stack (on tunnel input functions), where compiler has full
control of the alignment.
Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
diff --git a/net/openvswitch/flow.h b/net/openvswitch/flow.h
index ddcebc5..a292bf8 100644
--- a/net/openvswitch/flow.h
+++ b/net/openvswitch/flow.h
@@ -47,7 +47,7 @@
__be16 tun_flags;
u8 ipv4_tos;
u8 ipv4_ttl;
-};
+} __packed __aligned(4); /* Minimize padding. */
static inline void ovs_flow_tun_key_init(struct ovs_key_ipv4_tunnel *tun_key,
const struct iphdr *iph, __be64 tun_id,
@@ -71,7 +71,7 @@
u32 priority; /* Packet QoS priority. */
u32 skb_mark; /* SKB mark. */
u16 in_port; /* Input switch port (or DP_MAX_PORTS). */
- } phy;
+ } __packed phy; /* Safe when right after 'tun_key'. */
struct {
u8 src[ETH_ALEN]; /* Ethernet source address. */
u8 dst[ETH_ALEN]; /* Ethernet destination address. */
@@ -84,23 +84,21 @@
u8 ttl; /* IP TTL/hop limit. */
u8 frag; /* One of OVS_FRAG_TYPE_*. */
} ip;
+ struct {
+ __be16 src; /* TCP/UDP/SCTP source port. */
+ __be16 dst; /* TCP/UDP/SCTP destination port. */
+ __be16 flags; /* TCP flags. */
+ } tp;
union {
struct {
struct {
__be32 src; /* IP source address. */
__be32 dst; /* IP destination address. */
} addr;
- union {
- struct {
- __be16 src; /* TCP/UDP/SCTP source port. */
- __be16 dst; /* TCP/UDP/SCTP destination port. */
- __be16 flags; /* TCP flags. */
- } tp;
- struct {
- u8 sha[ETH_ALEN]; /* ARP source hardware address. */
- u8 tha[ETH_ALEN]; /* ARP target hardware address. */
- } arp;
- };
+ struct {
+ u8 sha[ETH_ALEN]; /* ARP source hardware address. */
+ u8 tha[ETH_ALEN]; /* ARP target hardware address. */
+ } arp;
} ipv4;
struct {
struct {
@@ -109,11 +107,6 @@
} addr;
__be32 label; /* IPv6 flow label. */
struct {
- __be16 src; /* TCP/UDP/SCTP source port. */
- __be16 dst; /* TCP/UDP/SCTP destination port. */
- __be16 flags; /* TCP flags. */
- } tp;
- struct {
struct in6_addr target; /* ND target address. */
u8 sll[ETH_ALEN]; /* ND source link layer address. */
u8 tll[ETH_ALEN]; /* ND target link layer address. */