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openvswitch: Compact sw_flow_key.

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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>
This commit is contained in:
Jarno Rajahalme 2014-05-05 09:54:49 -07:00 • committed by Pravin B Shelar
parent 091b64868b
commit 1139e241ec
3 changed files with 62 additions and 123 deletions
Download patch file Download diff file Expand all files Collapse all files

29
net/openvswitch/flow.h
View file

@ -47,7 +47,7 @@ struct ovs_key_ipv4_tunnel {
__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 @@ struct sw_flow_key {
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 @@ struct sw_flow_key {
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 {
@ -108,11 +106,6 @@ struct sw_flow_key {
struct in6_addr dst; /* IPv6 destination address. */
} 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. */