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lib/ofpbuf: Compact

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This patch shrinks the struct ofpbuf from 104 to 48 bytes on 64-bit
systems, or from 52 to 36 bytes on 32-bit systems (counting in the
'l7' removal from an earlier patch).  This may help contribute to
cache efficiency, and will speed up initializing, copying and
manipulating ofpbufs.  This is potentially important for the DPDK
datapath, but the rest of the code base may also see a little benefit.

Changes are:

- Remove 'l7' pointer (previous patch).
- Use offsets instead of layer pointers for l2_5, l3, and l4 using
  'l2' as basis.  Usually 'data' is the same as 'l2', but this is not
  always the case (e.g., when parsing or constructing a packet), so it
  can not be easily used as the offset basis.  Also, packet parsing is
  faster if we do not need to maintain the offsets each time we pull
  data from the ofpbuf.
- Use uint32_t for 'allocated' and 'size', as 2^32 is enough even for
  largest possible messages/packets.
- Use packed enum for 'source'.
- Rearrange to avoid unnecessary padding.
- Remove 'private_p', which was used only in two cases, both of which
  had the invariant ('l2' == 'data'), so we can temporarily use 'l2'
  as a private pointer.

Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>
This commit is contained in:
Jarno Rajahalme
2014-03-24 09:17:01 -07:00
parent d81eef1b87
commit 437d0d22ab
23 changed files with 278 additions and 218 deletions
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82
lib/flow.c
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@@ -338,18 +338,20 @@ invalid:
/* Initializes 'flow' members from 'packet' and 'md'
*
* Initializes 'packet' header pointers as follows:
* Initializes 'packet' header l2 pointer to the start of the Ethernet
* header, and the layer offsets as follows:
*
* - packet->l2 to the start of the Ethernet header.
* - packet->l2_5_ofs to the start of the MPLS shim header, or UINT16_MAX
* when there is no MPLS shim header.
*
* - packet->l2_5 to the start of the MPLS shim header.
*
* - packet->l3 to just past the Ethernet header, or just past the
* - packet->l3_ofs to just past the Ethernet header, or just past the
* vlan_header if one is present, to the first byte of the payload of the
* Ethernet frame.
* Ethernet frame. UINT16_MAX if the frame is too short to contain an
* Ethernet header.
*
* - packet->l4 to just past the IPv4 header, if one is present and has a
* correct length, and otherwise NULL.
* - packet->l4_ofs to just past the IPv4 header, if one is present and
* has at least the content used for the fields of interest for the flow,
* otherwise UINT16_MAX.
*/
void
flow_extract(struct ofpbuf *packet, const struct pkt_metadata *md,
@@ -370,9 +372,9 @@ flow_extract(struct ofpbuf *packet, const struct pkt_metadata *md,
}
packet->l2 = b.data;
packet->l2_5 = NULL;
packet->l3 = NULL;
packet->l4 = NULL;
ofpbuf_set_l2_5(packet, NULL);
ofpbuf_set_l3(packet, NULL);
ofpbuf_set_l4(packet, NULL);
if (b.size < sizeof *eth) {
return;
@@ -392,16 +394,16 @@ flow_extract(struct ofpbuf *packet, const struct pkt_metadata *md,
/* Parse mpls, copy l3 ttl. */
if (eth_type_mpls(flow->dl_type)) {
packet->l2_5 = b.data;
ofpbuf_set_l2_5(packet, b.data);
parse_mpls(&b, flow);
}
/* Network layer. */
packet->l3 = b.data;
ofpbuf_set_l3(packet, b.data);
if (flow->dl_type == htons(ETH_TYPE_IP)) {
const struct ip_header *nh = pull_ip(&b);
if (nh) {
packet->l4 = b.data;
ofpbuf_set_l4(packet, b.data);
flow->nw_src = get_16aligned_be32(&nh->ip_src);
flow->nw_dst = get_16aligned_be32(&nh->ip_dst);
@@ -437,7 +439,7 @@ flow_extract(struct ofpbuf *packet, const struct pkt_metadata *md,
return;
}
packet->l4 = b.data;
ofpbuf_set_l4(packet, b.data);
if (flow->nw_proto == IPPROTO_TCP) {
parse_tcp(&b, flow);
} else if (flow->nw_proto == IPPROTO_UDP) {
@@ -1237,45 +1239,48 @@ flow_set_mpls_lse(struct flow *flow, int idx, ovs_be32 lse)
flow->mpls_lse[idx] = lse;
}
static uint8_t *
static size_t
flow_compose_l4(struct ofpbuf *b, const struct flow *flow)
{
size_t l4_len = 0;
if (!(flow->nw_frag & FLOW_NW_FRAG_ANY)
|| !(flow->nw_frag & FLOW_NW_FRAG_LATER)) {
if (flow->nw_proto == IPPROTO_TCP) {
struct tcp_header *tcp;
tcp = ofpbuf_put_zeros(b, sizeof *tcp);
l4_len = sizeof *tcp;
tcp = ofpbuf_put_zeros(b, l4_len);
tcp->tcp_src = flow->tp_src;
tcp->tcp_dst = flow->tp_dst;
tcp->tcp_ctl = TCP_CTL(ntohs(flow->tcp_flags), 5);
return ofpbuf_tail(b);
} else if (flow->nw_proto == IPPROTO_UDP) {
struct udp_header *udp;
udp = ofpbuf_put_zeros(b, sizeof *udp);
l4_len = sizeof *udp;
udp = ofpbuf_put_zeros(b, l4_len);
udp->udp_src = flow->tp_src;
udp->udp_dst = flow->tp_dst;
return ofpbuf_tail(b);
} else if (flow->nw_proto == IPPROTO_SCTP) {
struct sctp_header *sctp;
sctp = ofpbuf_put_zeros(b, sizeof *sctp);
l4_len = sizeof *sctp;
sctp = ofpbuf_put_zeros(b, l4_len);
sctp->sctp_src = flow->tp_src;
sctp->sctp_dst = flow->tp_dst;
return ofpbuf_tail(b);
} else if (flow->nw_proto == IPPROTO_ICMP) {
struct icmp_header *icmp;
icmp = ofpbuf_put_zeros(b, sizeof *icmp);
l4_len = sizeof *icmp;
icmp = ofpbuf_put_zeros(b, l4_len);
icmp->icmp_type = ntohs(flow->tp_src);
icmp->icmp_code = ntohs(flow->tp_dst);
icmp->icmp_csum = csum(icmp, ICMP_HEADER_LEN);
return ofpbuf_tail(b);
} else if (flow->nw_proto == IPPROTO_ICMPV6) {
struct icmp6_hdr *icmp;
icmp = ofpbuf_put_zeros(b, sizeof *icmp);
l4_len = sizeof *icmp;
icmp = ofpbuf_put_zeros(b, l4_len);
icmp->icmp6_type = ntohs(flow->tp_src);
icmp->icmp6_code = ntohs(flow->tp_dst);
@@ -1285,16 +1290,19 @@ flow_compose_l4(struct ofpbuf *b, const struct flow *flow)
struct in6_addr *nd_target;
struct nd_opt_hdr *nd_opt;
l4_len += sizeof *nd_target;
nd_target = ofpbuf_put_zeros(b, sizeof *nd_target);
*nd_target = flow->nd_target;
if (!eth_addr_is_zero(flow->arp_sha)) {
l4_len += 8;
nd_opt = ofpbuf_put_zeros(b, 8);
nd_opt->nd_opt_len = 1;
nd_opt->nd_opt_type = ND_OPT_SOURCE_LINKADDR;
memcpy(nd_opt + 1, flow->arp_sha, ETH_ADDR_LEN);
}
if (!eth_addr_is_zero(flow->arp_tha)) {
l4_len += 8;
nd_opt = ofpbuf_put_zeros(b, 8);
nd_opt->nd_opt_len = 1;
nd_opt->nd_opt_type = ND_OPT_TARGET_LINKADDR;
@@ -1303,10 +1311,9 @@ flow_compose_l4(struct ofpbuf *b, const struct flow *flow)
}
icmp->icmp6_cksum = (OVS_FORCE uint16_t)
csum(icmp, (char *)ofpbuf_tail(b) - (char *)icmp);
return ofpbuf_tail(b);
}
}
return NULL;
return l4_len;
}
/* Puts into 'b' a packet that flow_extract() would parse as having the given
@@ -1318,6 +1325,8 @@ flow_compose_l4(struct ofpbuf *b, const struct flow *flow)
void
flow_compose(struct ofpbuf *b, const struct flow *flow)
{
size_t l4_len;
/* eth_compose() sets l3 pointer and makes sure it is 32-bit aligned. */
eth_compose(b, flow->dl_dst, flow->dl_src, ntohs(flow->dl_type), 0);
if (flow->dl_type == htons(FLOW_DL_TYPE_NONE)) {
@@ -1348,16 +1357,14 @@ flow_compose(struct ofpbuf *b, const struct flow *flow)
}
}
b->l4 = ofpbuf_tail(b);
ofpbuf_set_l4(b, ofpbuf_tail(b));
flow_compose_l4(b, flow);
l4_len = flow_compose_l4(b, flow);
ip->ip_tot_len = htons((uint8_t *) b->data + b->size
- (uint8_t *) b->l3);
ip->ip_tot_len = htons(b->l4_ofs - b->l3_ofs + l4_len);
ip->ip_csum = csum(ip, sizeof *ip);
} else if (flow->dl_type == htons(ETH_TYPE_IPV6)) {
struct ovs_16aligned_ip6_hdr *nh;
uint8_t *l7;
nh = ofpbuf_put_zeros(b, sizeof *nh);
put_16aligned_be32(&nh->ip6_flow, htonl(6 << 28) |
@@ -1368,16 +1375,17 @@ flow_compose(struct ofpbuf *b, const struct flow *flow)
memcpy(&nh->ip6_src, &flow->ipv6_src, sizeof(nh->ip6_src));
memcpy(&nh->ip6_dst, &flow->ipv6_dst, sizeof(nh->ip6_dst));
b->l4 = ofpbuf_tail(b);
ofpbuf_set_l4(b, ofpbuf_tail(b));
l7 = flow_compose_l4(b, flow);
l4_len = flow_compose_l4(b, flow);
nh->ip6_plen = l7 ? htons(l7 - (uint8_t *) b->l4) : htons(0);
nh->ip6_plen = htons(l4_len);
} else if (flow->dl_type == htons(ETH_TYPE_ARP) ||
flow->dl_type == htons(ETH_TYPE_RARP)) {
struct arp_eth_header *arp;
b->l3 = arp = ofpbuf_put_zeros(b, sizeof *arp);
arp = ofpbuf_put_zeros(b, sizeof *arp);
ofpbuf_set_l3(b, arp);
arp->ar_hrd = htons(1);
arp->ar_pro = htons(ETH_TYPE_IP);
arp->ar_hln = ETH_ADDR_LEN;
@@ -1396,7 +1404,7 @@ flow_compose(struct ofpbuf *b, const struct flow *flow)
if (eth_type_mpls(flow->dl_type)) {
int n;
b->l2_5 = b->l3;
b->l2_5_ofs = b->l3_ofs;
for (n = 1; n < FLOW_MAX_MPLS_LABELS; n++) {
if (flow->mpls_lse[n - 1] & htonl(MPLS_BOS_MASK)) {
break;