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Message-Id: <20230807122617.85882-1-huangjie.albert@bytedance.com>
Date: Mon, 7 Aug 2023 20:26:17 +0800
From: Albert Huang <huangjie.albert@...edance.com>
To:
Cc: Albert Huang <huangjie.albert@...edance.com>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Jesper Dangaard Brouer <hawk@...nel.org>,
John Fastabend <john.fastabend@...il.com>,
netdev@...r.kernel.org (open list:NETWORKING DRIVERS),
linux-kernel@...r.kernel.org (open list),
bpf@...r.kernel.org (open list:XDP (eXpress Data Path))
Subject: [RFC v2 Optimizing veth xsk performance 8/9] veth: af_xdp tx batch support for ipv4 udp
A typical topology is shown below:
veth<--------veth-peer
1 |
|2
|
bridge<------->eth0(such as mlnx5 NIC)
If you use af_xdp to send packets from veth to a physical NIC,
it needs to go through some software paths, so we can refer to
the implementation of kernel GSO. When af_xdp sends packets out
from veth, consider aggregating packets and send a large packet
from the veth virtual NIC to the physical NIC.
performance:(test weth libxdp lib)
AF_XDP without batch : 480 Kpps (with ksoftirqd 100% cpu)
AF_XDP with batch : 1.5 Mpps (with ksoftirqd 15% cpu)
With af_xdp batch, the libxdp user-space program reaches a bottleneck.
Therefore, the softirq did not reach the limit.
Signed-off-by: Albert Huang <huangjie.albert@...edance.com>
---
drivers/net/veth.c | 408 ++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 387 insertions(+), 21 deletions(-)
diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index ac78d6a87416..70489d017b51 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -29,6 +29,7 @@
#include <net/page_pool.h>
#include <net/xdp_sock_drv.h>
#include <net/xdp.h>
+#include <net/udp.h>
#define DRV_NAME "veth"
#define DRV_VERSION "1.0"
@@ -103,6 +104,23 @@ struct veth_xdp_tx_bq {
unsigned int count;
};
+struct veth_batch_tuple {
+ __u8 protocol;
+ __be32 saddr;
+ __be32 daddr;
+ __be16 source;
+ __be16 dest;
+ __be16 batch_size;
+ __be16 batch_segs;
+ bool batch_enable;
+ bool batch_flush;
+};
+
+struct veth_seg_info {
+ u32 segs;
+ u64 desc[] ____cacheline_aligned_in_smp;
+};
+
/*
* ethtool interface
*/
@@ -1078,11 +1096,340 @@ static struct sk_buff *veth_build_skb(void *head, int headroom, int len,
return skb;
}
+static void veth_xsk_destruct_skb(struct sk_buff *skb)
+{
+ struct skb_shared_info *si = skb_shinfo(skb);
+ struct xsk_buff_pool *pool = (struct xsk_buff_pool *)si->destructor_arg_xsk_pool;
+ struct veth_seg_info *seg_info = (struct veth_seg_info *)si->destructor_arg;
+ unsigned long flags;
+ u32 index = 0;
+ u64 addr;
+
+ /* release cq */
+ spin_lock_irqsave(&pool->cq_lock, flags);
+ for (index = 0; index < seg_info->segs; index++) {
+ addr = (u64)(long)seg_info->desc[index];
+ xsk_tx_completed_addr(pool, addr);
+ }
+ spin_unlock_irqrestore(&pool->cq_lock, flags);
+
+ kfree(seg_info);
+ si->destructor_arg = NULL;
+ si->destructor_arg_xsk_pool = NULL;
+}
+
+static struct sk_buff *veth_build_gso_head_skb(struct net_device *dev,
+ char *buff, u32 tot_len,
+ u32 headroom, u32 iph_len,
+ u32 th_len)
+{
+ struct sk_buff *skb = NULL;
+ int err = 0;
+
+ skb = alloc_skb(tot_len, GFP_KERNEL);
+ if (unlikely(!skb))
+ return NULL;
+
+ /* header room contains the eth header */
+ skb_reserve(skb, headroom - ETH_HLEN);
+ skb_put(skb, ETH_HLEN + iph_len + th_len);
+ skb_shinfo(skb)->gso_segs = 0;
+
+ err = skb_store_bits(skb, 0, buff, ETH_HLEN + iph_len + th_len);
+ if (unlikely(err)) {
+ kfree_skb(skb);
+ return NULL;
+ }
+
+ skb->protocol = eth_type_trans(skb, dev);
+ skb->network_header = skb->mac_header + ETH_HLEN;
+ skb->transport_header = skb->network_header + iph_len;
+ skb->ip_summed = CHECKSUM_PARTIAL;
+
+ return skb;
+}
+
+/* only ipv4 udp match
+ * to do: tcp and ipv6
+ */
+static inline bool veth_segment_match(struct veth_batch_tuple *tuple,
+ struct iphdr *iph, struct udphdr *udph)
+{
+ if (tuple->protocol == iph->protocol &&
+ tuple->saddr == iph->saddr &&
+ tuple->daddr == iph->daddr &&
+ tuple->source == udph->source &&
+ tuple->dest == udph->dest &&
+ tuple->batch_size == ntohs(udph->len)) {
+ tuple->batch_flush = false;
+ return true;
+ }
+
+ tuple->batch_flush = true;
+ return false;
+}
+
+static inline void veth_tuple_init(struct veth_batch_tuple *tuple,
+ struct iphdr *iph, struct udphdr *udph)
+{
+ tuple->protocol = iph->protocol;
+ tuple->saddr = iph->saddr;
+ tuple->daddr = iph->daddr;
+ tuple->source = udph->source;
+ tuple->dest = udph->dest;
+ tuple->batch_flush = false;
+ tuple->batch_size = ntohs(udph->len);
+ tuple->batch_segs = 0;
+}
+
+static inline bool veth_batch_ip_check_v4(struct iphdr *iph, u32 len)
+{
+ if (len <= (ETH_HLEN + sizeof(*iph)))
+ return false;
+
+ if (iph->ihl < 5 || iph->version != 4 || len < (iph->ihl * 4 + ETH_HLEN))
+ return false;
+
+ return true;
+}
+
+static struct sk_buff *veth_build_skb_batch_udp(struct net_device *dev,
+ struct xsk_buff_pool *pool,
+ struct xdp_desc *desc,
+ struct veth_batch_tuple *tuple,
+ struct sk_buff *prev_skb)
+{
+ u32 hr, len, ts, index, iph_len, th_len, data_offset, data_len, tot_len;
+ struct veth_seg_info *seg_info;
+ void *buffer;
+ struct udphdr *udph;
+ struct iphdr *iph;
+ struct sk_buff *skb;
+ struct page *page;
+ u32 seg_len = 0;
+ int hh_len = 0;
+ u64 addr;
+
+ addr = desc->addr;
+ len = desc->len;
+
+ /* l2 reserved len */
+ hh_len = LL_RESERVED_SPACE(dev);
+ hr = max(NET_SKB_PAD, L1_CACHE_ALIGN(hh_len));
+
+ /* data points to eth header */
+ buffer = (unsigned char *)xsk_buff_raw_get_data(pool, addr);
+
+ iph = (struct iphdr *)(buffer + ETH_HLEN);
+ iph_len = iph->ihl * 4;
+
+ udph = (struct udphdr *)(buffer + ETH_HLEN + iph_len);
+ th_len = sizeof(struct udphdr);
+
+ if (tuple->batch_flush)
+ veth_tuple_init(tuple, iph, udph);
+
+ ts = pool->unaligned ? len : pool->chunk_size;
+
+ data_offset = offset_in_page(buffer) + ETH_HLEN + iph_len + th_len;
+ data_len = len - (ETH_HLEN + iph_len + th_len);
+
+ /* head is null or this is a new 5 tuple */
+ if (!prev_skb || !veth_segment_match(tuple, iph, udph)) {
+ tot_len = hr + iph_len + th_len;
+ skb = veth_build_gso_head_skb(dev, buffer, tot_len, hr, iph_len, th_len);
+ if (!skb) {
+ /* to do: handle here for skb */
+ return NULL;
+ }
+
+ /* store information for gso */
+ seg_len = struct_size(seg_info, desc, MAX_SKB_FRAGS);
+ seg_info = kmalloc(seg_len, GFP_KERNEL);
+ if (!seg_info) {
+ /* to do */
+ kfree_skb(skb);
+ return NULL;
+ }
+ } else {
+ skb = prev_skb;
+ skb_shinfo(skb)->gso_type = SKB_GSO_UDP_L4 | SKB_GSO_PARTIAL;
+ skb_shinfo(skb)->gso_size = data_len;
+ skb->ip_summed = CHECKSUM_PARTIAL;
+
+ /* max segment is MAX_SKB_FRAGS */
+ if (skb_shinfo(skb)->gso_segs >= MAX_SKB_FRAGS - 1)
+ tuple->batch_flush = true;
+
+ seg_info = (struct veth_seg_info *)skb_shinfo(skb)->destructor_arg;
+ }
+
+ /* offset in umem pool buffer */
+ addr = buffer - pool->addrs;
+
+ /* get the page of the desc */
+ page = pool->umem->pgs[addr >> PAGE_SHIFT];
+
+ /* in order to avoid to get freed by kfree_skb */
+ get_page(page);
+
+ /* desc.data can not hold in two */
+ skb_fill_page_desc(skb, skb_shinfo(skb)->gso_segs, page, data_offset, data_len);
+
+ skb->len += data_len;
+ skb->data_len += data_len;
+ skb->truesize += ts;
+ skb->dev = dev;
+
+ /* later we will support gso for this */
+ index = skb_shinfo(skb)->gso_segs;
+ seg_info->desc[index] = desc->addr;
+ seg_info->segs = ++index;
+ skb_shinfo(skb)->gso_segs++;
+
+ skb_shinfo(skb)->destructor_arg = (void *)(long)seg_info;
+ skb_shinfo(skb)->destructor_arg_xsk_pool = (void *)(long)pool;
+ skb->destructor = veth_xsk_destruct_skb;
+
+ /* to do:
+ * add skb to sock. may be there is no need to do for this
+ * and this might be multiple xsk sockets involved, so it's
+ * difficult to determine which socket is sending the data.
+ * refcount_add(ts, &xs->sk.sk_wmem_alloc);
+ */
+ return skb;
+}
+
+static inline struct sk_buff *veth_build_skb_def(struct net_device *dev,
+ struct xsk_buff_pool *pool, struct xdp_desc *desc)
+{
+ struct sk_buff *skb = NULL;
+ struct page *page;
+ void *buffer;
+ void *vaddr;
+
+ page = dev_alloc_page();
+ if (!page)
+ return NULL;
+
+ buffer = (unsigned char *)xsk_buff_raw_get_data(pool, desc->addr);
+
+ vaddr = page_to_virt(page);
+ memcpy(vaddr + pool->headroom, buffer, desc->len);
+ skb = veth_build_skb(vaddr, pool->headroom, desc->len, PAGE_SIZE);
+ if (!skb) {
+ put_page(page);
+ return NULL;
+ }
+
+ skb->protocol = eth_type_trans(skb, dev);
+
+ return skb;
+}
+
+/* To call the following function, the following conditions must be met:
+ * 1.The data packet must be a standard Ethernet data packet
+ * 2. Data packets support batch sending
+ */
+static inline struct sk_buff *veth_build_skb_batch_v4(struct net_device *dev,
+ struct xsk_buff_pool *pool,
+ struct xdp_desc *desc,
+ struct veth_batch_tuple *tuple,
+ struct sk_buff *prev_skb)
+{
+ struct iphdr *iph;
+ void *buffer;
+ u64 addr;
+
+ addr = desc->addr;
+ buffer = (unsigned char *)xsk_buff_raw_get_data(pool, addr);
+ iph = (struct iphdr *)(buffer + ETH_HLEN);
+ if (!veth_batch_ip_check_v4(iph, desc->len))
+ goto normal;
+
+ switch (iph->protocol) {
+ case IPPROTO_UDP:
+ return veth_build_skb_batch_udp(dev, pool, desc, tuple, prev_skb);
+ default:
+ break;
+ }
+normal:
+ tuple->batch_enable = false;
+ return veth_build_skb_def(dev, pool, desc);
+}
+
+/* Zero copy needs to meet the following conditions：
+ * 1. The data content of tx desc must be within one page
+ * 2、the tx desc must support batch xmit, which seted by userspace
+ */
+static inline bool veth_batch_desc_check(void *buff, u32 len)
+{
+ u32 offset;
+
+ offset = offset_in_page(buff);
+ if (PAGE_SIZE - offset < len)
+ return false;
+
+ return true;
+}
+
+/* here must be a ipv4 or ipv6 packet */
+static inline struct sk_buff *veth_build_skb_batch(struct net_device *dev,
+ struct xsk_buff_pool *pool,
+ struct xdp_desc *desc,
+ struct veth_batch_tuple *tuple,
+ struct sk_buff *prev_skb)
+{
+ const struct ethhdr *eth;
+ void *buffer;
+
+ buffer = xsk_buff_raw_get_data(pool, desc->addr);
+ if (!veth_batch_desc_check(buffer, desc->len))
+ goto normal;
+
+ eth = (struct ethhdr *)buffer;
+ switch (ntohs(eth->h_proto)) {
+ case ETH_P_IP:
+ tuple->batch_enable = true;
+ return veth_build_skb_batch_v4(dev, pool, desc, tuple, prev_skb);
+ /* to do: not support yet, just build skb, no batch */
+ case ETH_P_IPV6:
+ fallthrough;
+ default:
+ break;
+ }
+
+normal:
+ tuple->batch_flush = false;
+ tuple->batch_enable = false;
+ return veth_build_skb_def(dev, pool, desc);
+}
+
+/* just support ipv4 udp batch
+ * to do: ipv4 tcp and ipv6
+ */
+static inline void veth_skb_batch_checksum(struct sk_buff *skb)
+{
+ struct iphdr *iph = ip_hdr(skb);
+ struct udphdr *uh = udp_hdr(skb);
+ int ip_tot_len = skb->len;
+ int udp_len = skb->len - (skb->transport_header - skb->network_header);
+
+ iph->tot_len = htons(ip_tot_len);
+ ip_send_check(iph);
+ uh->len = htons(udp_len);
+ uh->check = 0;
+
+ udp4_hwcsum(skb, iph->saddr, iph->daddr);
+}
+
static int veth_xsk_tx_xmit(struct veth_sq *sq, struct xsk_buff_pool *xsk_pool, int budget)
{
struct veth_priv *priv, *peer_priv;
struct net_device *dev, *peer_dev;
+ struct veth_batch_tuple tuple;
struct veth_stats stats = {};
+ struct sk_buff *prev_skb = NULL;
struct sk_buff *skb = NULL;
struct veth_rq *peer_rq;
struct xdp_desc desc;
@@ -1093,24 +1440,23 @@ static int veth_xsk_tx_xmit(struct veth_sq *sq, struct xsk_buff_pool *xsk_pool,
peer_dev = priv->peer;
peer_priv = netdev_priv(peer_dev);
- /* todo: queue index must set before this */
+ /* queue_index set in napi enable
+ * to do:may be we should select rq by 5-tuple or hash
+ */
peer_rq = &peer_priv->rq[sq->queue_index];
+ memset(&tuple, 0, sizeof(tuple));
+
/* set xsk wake up flag, to do: where to disable */
if (xsk_uses_need_wakeup(xsk_pool))
xsk_set_tx_need_wakeup(xsk_pool);
while (budget-- > 0) {
unsigned int truesize = 0;
- struct page *page;
- void *vaddr;
- void *addr;
if (!xsk_tx_peek_desc(xsk_pool, &desc))
break;
- addr = xsk_buff_raw_get_data(xsk_pool, desc.addr);
-
/* can not hold all data in a page */
truesize = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
truesize += desc.len + xsk_pool->headroom;
@@ -1120,30 +1466,50 @@ static int veth_xsk_tx_xmit(struct veth_sq *sq, struct xsk_buff_pool *xsk_pool,
break;
}
- page = dev_alloc_page();
- if (!page) {
+ skb = veth_build_skb_batch(peer_dev, xsk_pool, &desc, &tuple, prev_skb);
+ if (!skb) {
+ stats.rx_drops++;
xsk_tx_completed_addr(xsk_pool, desc.addr);
- stats.xdp_drops++;
- break;
+ if (prev_skb != skb) {
+ napi_gro_receive(&peer_rq->xdp_napi, prev_skb);
+ prev_skb = NULL;
+ }
+ continue;
}
- vaddr = page_to_virt(page);
-
- memcpy(vaddr + xsk_pool->headroom, addr, desc.len);
- xsk_tx_completed_addr(xsk_pool, desc.addr);
- skb = veth_build_skb(vaddr, xsk_pool->headroom, desc.len, PAGE_SIZE);
- if (!skb) {
- put_page(page);
- stats.xdp_drops++;
- break;
+ if (!tuple.batch_enable) {
+ xsk_tx_completed_addr(xsk_pool, desc.addr);
+ /* flush the prev skb first to avoid out of order */
+ if (prev_skb != skb && prev_skb) {
+ veth_skb_batch_checksum(prev_skb);
+ napi_gro_receive(&peer_rq->xdp_napi, prev_skb);
+ prev_skb = NULL;
+ }
+ napi_gro_receive(&peer_rq->xdp_napi, skb);
+ skb = NULL;
+ } else {
+ if (prev_skb && tuple.batch_flush) {
+ veth_skb_batch_checksum(prev_skb);
+ napi_gro_receive(&peer_rq->xdp_napi, prev_skb);
+ if (prev_skb == skb)
+ prev_skb = skb = NULL;
+ else
+ prev_skb = skb;
+ } else {
+ prev_skb = skb;
+ }
}
- skb->protocol = eth_type_trans(skb, peer_dev);
- napi_gro_receive(&peer_rq->xdp_napi, skb);
stats.xdp_bytes += desc.len;
done++;
}
+ /* means there is a skb need to send to peer_rq (batch)*/
+ if (skb) {
+ veth_skb_batch_checksum(skb);
+ napi_gro_receive(&peer_rq->xdp_napi, skb);
+ }
+
/* release, move consumer，and wakeup the producer */
if (done) {
napi_schedule(&peer_rq->xdp_napi);
--
2.20.1
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