On 2/25/22 01:02, Harold Huang wrote:
In tun, NAPI is supported and we can also use NAPI in the path of
batched XDP buffs to accelerate packet processing. What is more, after
we use NAPI, GRO is also supported. The iperf shows that the throughput of
single stream could be improved from 4.5Gbps to 9.2Gbps. Additionally, 9.2
Gbps nearly reachs the line speed of the phy nic and there is still about
15% idle cpu core remaining on the vhost thread.
Test topology:
[iperf server]<--->tap<--->dpdk testpmd<--->phy nic<--->[iperf client]
Iperf stream:
Before:
...
[ 5] 5.00-6.00 sec 558 MBytes 4.68 Gbits/sec 0 1.50 MBytes
[ 5] 6.00-7.00 sec 556 MBytes 4.67 Gbits/sec 1 1.35 MBytes
[ 5] 7.00-8.00 sec 556 MBytes 4.67 Gbits/sec 2 1.18 MBytes
[ 5] 8.00-9.00 sec 559 MBytes 4.69 Gbits/sec 0 1.48 MBytes
[ 5] 9.00-10.00 sec 556 MBytes 4.67 Gbits/sec 1 1.33 MBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 5.39 GBytes 4.63 Gbits/sec 72 sender
[ 5] 0.00-10.04 sec 5.39 GBytes 4.61 Gbits/sec receiver
After:
...
[ 5] 5.00-6.00 sec 1.07 GBytes 9.19 Gbits/sec 0 1.55 MBytes
[ 5] 6.00-7.00 sec 1.08 GBytes 9.30 Gbits/sec 0 1.63 MBytes
[ 5] 7.00-8.00 sec 1.08 GBytes 9.25 Gbits/sec 0 1.72 MBytes
[ 5] 8.00-9.00 sec 1.08 GBytes 9.25 Gbits/sec 77 1.31 MBytes
[ 5] 9.00-10.00 sec 1.08 GBytes 9.24 Gbits/sec 0 1.48 MBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 10.8 GBytes 9.28 Gbits/sec 166 sender
[ 5] 0.00-10.04 sec 10.8 GBytes 9.24 Gbits/sec receiver
....
Reported-at: https://lore.kernel.org/all/CACGkMEvTLG0Ayg+TtbN4q4pPW-ycgCCs3sC3-TF8cuRTf7Pp1A@xxxxxxxxxxxxxx
Signed-off-by: Harold Huang <baymaxhuang@xxxxxxxxx>
---
v1 -> v2
- fix commit messages
- add queued flag to avoid void unnecessary napi suggested by Jason
drivers/net/tun.c | 20 ++++++++++++++++----
1 file changed, 16 insertions(+), 4 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index fed85447701a..c7d8b7c821d8 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -2379,7 +2379,7 @@ static void tun_put_page(struct tun_page *tpage)
}
static int tun_xdp_one(struct tun_struct *tun,
- struct tun_file *tfile,
+ struct tun_file *tfile, int *queued,
struct xdp_buff *xdp, int *flush,
struct tun_page *tpage)
{
@@ -2388,6 +2388,7 @@ static int tun_xdp_one(struct tun_struct *tun,
struct virtio_net_hdr *gso = &hdr->gso;
struct bpf_prog *xdp_prog;
struct sk_buff *skb = NULL;
+ struct sk_buff_head *queue;
u32 rxhash = 0, act;
int buflen = hdr->buflen;
int err = 0;
@@ -2464,7 +2465,15 @@ static int tun_xdp_one(struct tun_struct *tun,
!tfile->detached)
rxhash = __skb_get_hash_symmetric(skb);
- netif_receive_skb(skb);
+ if (tfile->napi_enabled) {
+ queue = &tfile->sk.sk_write_queue;
+ spin_lock(&queue->lock);
+ __skb_queue_tail(queue, skb);
+ spin_unlock(&queue->lock);
+ (*queued)++;
+ } else {
+ netif_receive_skb(skb);
+ }
/* No need to disable preemption here since this function is
* always called with bh disabled
@@ -2492,7 +2501,7 @@ static int tun_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len)
if (ctl && (ctl->type == TUN_MSG_PTR)) {
struct tun_page tpage;
int n = ctl->num;
- int flush = 0;
+ int flush = 0, queued = 0;
memset(&tpage, 0, sizeof(tpage));
@@ -2501,12 +2510,15 @@ static int tun_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len)
for (i = 0; i < n; i++) {
xdp = &((struct xdp_buff *)ctl->ptr)[i];
- tun_xdp_one(tun, tfile, xdp, &flush, &tpage);
+ tun_xdp_one(tun, tfile, &queued, xdp, &flush, &tpage);
How big n can be ?
BTW I could not find where m->msg_controllen was checked in tun_sendmsg().
struct tun_msg_ctl *ctl = m->msg_control;
if (ctl && (ctl->type == TUN_MSG_PTR)) {
int n = ctl->num; // can be set to values in [0..65535]
for (i = 0; i < n; i++) {
xdp = &((struct xdp_buff *)ctl->ptr)[i];
I really do not understand how we prevent malicious user space from
crashing the kernel.
}
if (flush)
xdp_do_flush();
+ if (tfile->napi_enabled && queued > 0)
+ napi_schedule(&tfile->napi);
+
rcu_read_unlock();
local_bh_enable();
