From: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Alexander Lobakin <alobakin@pm.me>,
Jason Wang <jasowang@redhat.com>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
bjorn.topel@intel.com,
Magnus Karlsson <magnus.karlsson@intel.com>,
Jonathan Lemon <jonathan.lemon@gmail.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Jesper Dangaard Brouer <hawk@kernel.org>,
John Fastabend <john.fastabend@gmail.com>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>, KP Singh <kpsingh@kernel.org>,
virtualization@lists.linux-foundation.org, bpf@vger.kernel.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH net-next v2 3/3] xsk: build skb by page
Date: Wed, 20 Jan 2021 16:30:56 +0800 [thread overview]
Message-ID: <0461512be1925bece9bcda1b4924b09eaa4edd87.1611131344.git.xuanzhuo@linux.alibaba.com> (raw)
In-Reply-To: <20210120030418-mutt-send-email-mst@kernel.org>
In-Reply-To: <cover.1611131344.git.xuanzhuo@linux.alibaba.com>
This patch is used to construct skb based on page to save memory copy
overhead.
This function is implemented based on IFF_TX_SKB_NO_LINEAR. Only the
network card priv_flags supports IFF_TX_SKB_NO_LINEAR will use page to
directly construct skb. If this feature is not supported, it is still
necessary to copy data to construct skb.
---------------- Performance Testing ------------
The test environment is Aliyun ECS server.
Test cmd:
```
xdpsock -i eth0 -t -S -s <msg size>
```
Test result data:
size 64 512 1024 1500
copy 1916747 1775988 1600203 1440054
page 1974058 1953655 1945463 1904478
percent 3.0% 10.0% 21.58% 32.3%
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Reviewed-by: Dust Li <dust.li@linux.alibaba.com>
---
net/xdp/xsk.c | 104 ++++++++++++++++++++++++++++++++++++++++++++++++----------
1 file changed, 86 insertions(+), 18 deletions(-)
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 8037b04..40bac11 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -430,6 +430,87 @@ static void xsk_destruct_skb(struct sk_buff *skb)
sock_wfree(skb);
}
+static struct sk_buff *xsk_build_skb_zerocopy(struct xdp_sock *xs,
+ struct xdp_desc *desc)
+{
+ u32 len, offset, copy, copied;
+ struct sk_buff *skb;
+ struct page *page;
+ void *buffer;
+ int err, i;
+ u64 addr;
+
+ skb = sock_alloc_send_skb(&xs->sk, 0, 1, &err);
+ if (unlikely(!skb))
+ return ERR_PTR(err);
+
+ addr = desc->addr;
+ len = desc->len;
+
+ buffer = xsk_buff_raw_get_data(xs->pool, addr);
+ offset = offset_in_page(buffer);
+ addr = buffer - xs->pool->addrs;
+
+ for (copied = 0, i = 0; copied < len; i++) {
+ page = xs->pool->umem->pgs[addr >> PAGE_SHIFT];
+
+ get_page(page);
+
+ copy = min_t(u32, PAGE_SIZE - offset, len - copied);
+
+ skb_fill_page_desc(skb, i, page, offset, copy);
+
+ copied += copy;
+ addr += copy;
+ offset = 0;
+ }
+
+ skb->len += len;
+ skb->data_len += len;
+ skb->truesize += len;
+
+ refcount_add(len, &xs->sk.sk_wmem_alloc);
+
+ return skb;
+}
+
+static struct sk_buff *xsk_build_skb(struct xdp_sock *xs,
+ struct xdp_desc *desc)
+{
+ struct sk_buff *skb = NULL;
+
+ if (xs->dev->priv_flags & IFF_TX_SKB_NO_LINEAR) {
+ skb = xsk_build_skb_zerocopy(xs, desc);
+ if (IS_ERR(skb))
+ return skb;
+ } else {
+ void *buffer;
+ u32 len;
+ int err;
+
+ len = desc->len;
+ skb = sock_alloc_send_skb(&xs->sk, len, 1, &err);
+ if (unlikely(!skb))
+ return ERR_PTR(err);
+
+ skb_put(skb, len);
+ buffer = xsk_buff_raw_get_data(xs->pool, desc->addr);
+ err = skb_store_bits(skb, 0, buffer, len);
+ if (unlikely(err)) {
+ kfree_skb(skb);
+ return ERR_PTR(err);
+ }
+ }
+
+ skb->dev = xs->dev;
+ skb->priority = xs->sk.sk_priority;
+ skb->mark = xs->sk.sk_mark;
+ skb_shinfo(skb)->destructor_arg = (void *)(long)desc->addr;
+ skb->destructor = xsk_destruct_skb;
+
+ return skb;
+}
+
static int xsk_generic_xmit(struct sock *sk)
{
struct xdp_sock *xs = xdp_sk(sk);
@@ -446,43 +527,30 @@ static int xsk_generic_xmit(struct sock *sk)
goto out;
while (xskq_cons_peek_desc(xs->tx, &desc, xs->pool)) {
- char *buffer;
- u64 addr;
- u32 len;
-
if (max_batch-- == 0) {
err = -EAGAIN;
goto out;
}
- len = desc.len;
- skb = sock_alloc_send_skb(sk, len, 1, &err);
- if (unlikely(!skb))
+ skb = xsk_build_skb(xs, &desc);
+ if (IS_ERR(skb)) {
+ err = PTR_ERR(skb);
goto out;
+ }
- skb_put(skb, len);
- addr = desc.addr;
- buffer = xsk_buff_raw_get_data(xs->pool, addr);
- err = skb_store_bits(skb, 0, buffer, len);
/* This is the backpressure mechanism for the Tx path.
* Reserve space in the completion queue and only proceed
* if there is space in it. This avoids having to implement
* any buffering in the Tx path.
*/
spin_lock_irqsave(&xs->pool->cq_lock, flags);
- if (unlikely(err) || xskq_prod_reserve(xs->pool->cq)) {
+ if (xskq_prod_reserve(xs->pool->cq)) {
spin_unlock_irqrestore(&xs->pool->cq_lock, flags);
kfree_skb(skb);
goto out;
}
spin_unlock_irqrestore(&xs->pool->cq_lock, flags);
- skb->dev = xs->dev;
- skb->priority = sk->sk_priority;
- skb->mark = sk->sk_mark;
- skb_shinfo(skb)->destructor_arg = (void *)(long)desc.addr;
- skb->destructor = xsk_destruct_skb;
-
err = __dev_direct_xmit(skb, xs->queue_id);
if (err == NETDEV_TX_BUSY) {
/* Tell user-space to retry the send */
--
1.8.3.1
next prev parent reply other threads:[~2021-01-20 8:35 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <cover.1611048724.git.xuanzhuo@linux.alibaba.com>
[not found] ` <21d2f709140470eb143e3c6c69e2a5dbd20bf2e7.1611048724.git.xuanzhuo@linux.alibaba.com>
2021-01-19 14:28 ` [PATCH bpf-next v2 2/3] virtio-net: support IFF_TX_SKB_NO_LINEAR Alexander Lobakin
[not found] ` <cover.1611128806.git.xuanzhuo@linux.alibaba.com>
2021-01-20 7:49 ` [PATCH net-next " Xuan Zhuo
2021-01-20 7:57 ` Michael S. Tsirkin
2021-01-20 7:50 ` [PATCH net-next v2 3/3] xsk: build skb by page Xuan Zhuo
2021-01-20 8:10 ` Michael S. Tsirkin
2021-01-20 8:11 ` Michael S. Tsirkin
[not found] ` <cover.1611131344.git.xuanzhuo@linux.alibaba.com>
2021-01-20 8:30 ` Xuan Zhuo [this message]
2021-01-20 13:56 ` Alexander Lobakin
2021-01-21 7:41 ` Magnus Karlsson
2021-01-21 10:54 ` Yunsheng Lin
[not found] ` <017fdff4e061a7e0e779b7bc96ed3b45e07aa006.1611048724.git.xuanzhuo@linux.alibaba.com>
2021-01-19 14:43 ` [PATCH bpf-next " Alexander Lobakin
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