From bda56f143c9dc38ae7926ba21ebeb35359a6c051 Mon Sep 17 00:00:00 2001 From: Thomas Graf Date: Fri, 13 Dec 2013 15:22:21 +0100 Subject: openvswitch: Use skb_zerocopy() for upcall Use of skb_zerocopy() can avoid the expensive call to memcpy() when copying the packet data into the Netlink skb. Completes checksum through skb_checksum_help() if not already done in GSO segmentation. Zerocopy is only performed if user space supported unaligned Netlink messages. memory mapped netlink i/o is preferred over zerocopy if it is set up. Cost of upcall is significantly reduced from: + 7.48% vhost-8471 [k] memcpy + 5.57% ovs-vswitchd [k] memcpy + 2.81% vhost-8471 [k] csum_partial_copy_generic to: + 5.72% ovs-vswitchd [k] memcpy + 3.32% vhost-5153 [k] memcpy + 0.68% vhost-5153 [k] skb_zerocopy (megaflows disabled) Signed-off-by: Thomas Graf Signed-off-by: Jesse Gross --- net/openvswitch/datapath.c | 37 +++++++++++++++++++++++++++++-------- 1 file changed, 29 insertions(+), 8 deletions(-) (limited to 'net/openvswitch') diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c index 235acaeaedc7..85578342d566 100644 --- a/net/openvswitch/datapath.c +++ b/net/openvswitch/datapath.c @@ -371,11 +371,11 @@ static size_t key_attr_size(void) + nla_total_size(28); /* OVS_KEY_ATTR_ND */ } -static size_t upcall_msg_size(const struct sk_buff *skb, - const struct nlattr *userdata) +static size_t upcall_msg_size(const struct nlattr *userdata, + unsigned int hdrlen) { size_t size = NLMSG_ALIGN(sizeof(struct ovs_header)) - + nla_total_size(skb->len) /* OVS_PACKET_ATTR_PACKET */ + + nla_total_size(hdrlen) /* OVS_PACKET_ATTR_PACKET */ + nla_total_size(key_attr_size()); /* OVS_PACKET_ATTR_KEY */ /* OVS_PACKET_ATTR_USERDATA */ @@ -397,6 +397,7 @@ static int queue_userspace_packet(struct datapath *dp, struct sk_buff *skb, .snd_portid = upcall_info->portid, }; size_t len; + unsigned int hlen; int err, dp_ifindex; dp_ifindex = get_dpifindex(dp); @@ -421,7 +422,21 @@ static int queue_userspace_packet(struct datapath *dp, struct sk_buff *skb, goto out; } - len = upcall_msg_size(skb, upcall_info->userdata); + /* Complete checksum if needed */ + if (skb->ip_summed == CHECKSUM_PARTIAL && + (err = skb_checksum_help(skb))) + goto out; + + /* Older versions of OVS user space enforce alignment of the last + * Netlink attribute to NLA_ALIGNTO which would require extensive + * padding logic. Only perform zerocopy if padding is not required. + */ + if (dp->user_features & OVS_DP_F_UNALIGNED) + hlen = skb_zerocopy_headlen(skb); + else + hlen = skb->len; + + len = upcall_msg_size(upcall_info->userdata, hlen); user_skb = genlmsg_new_unicast(len, &info, GFP_ATOMIC); if (!user_skb) { err = -ENOMEM; @@ -441,13 +456,19 @@ static int queue_userspace_packet(struct datapath *dp, struct sk_buff *skb, nla_len(upcall_info->userdata), nla_data(upcall_info->userdata)); - nla = __nla_reserve(user_skb, OVS_PACKET_ATTR_PACKET, skb->len); + /* Only reserve room for attribute header, packet data is added + * in skb_zerocopy() */ + if (!(nla = nla_reserve(user_skb, OVS_PACKET_ATTR_PACKET, 0))) { + err = -ENOBUFS; + goto out; + } + nla->nla_len = nla_attr_size(skb->len); - skb_copy_and_csum_dev(skb, nla_data(nla)); + skb_zerocopy(user_skb, skb, skb->len, hlen); - genlmsg_end(user_skb, upcall); - err = genlmsg_unicast(ovs_dp_get_net(dp), user_skb, upcall_info->portid); + ((struct nlmsghdr *) user_skb->data)->nlmsg_len = user_skb->len; + err = genlmsg_unicast(ovs_dp_get_net(dp), user_skb, upcall_info->portid); out: kfree_skb(nskb); return err; -- cgit v1.2.3-59-g8ed1b