Commit 2613af0ed18a11d5c566a81f9a6510b73180660a (virtio_net: migrate mergeable
rx buffers to page frag allocators) try to increase the payload/truesize for
MTU-sized traffic. But this will introduce the extra overhead for GSO packets
received because of the frag list. This commit tries to reduce this issue by
coalesce the possible rx frags when possible during rx. Test result shows the
about 15% improvement on full size GSO packet receiving (and even better than
commit 2613af0ed18a11d5c566a81f9a6510b73180660a).
Before this commit:
./netperf -H 192.168.100.4
MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.100.4
() port 0 AF_INET : demo
Recv Send Send
Socket Socket Message Elapsed
Size Size Size Time Throughput
bytes bytes bytes secs. 10^6bits/sec
87380 16384 16384 10.00 20303.87
After this commit:
./netperf -H 192.168.100.4
MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.100.4 () port 0 AF_INET : demo
Recv Send Send
Socket Socket Message Elapsed
Size Size Size Time Throughput
bytes bytes bytes secs. 10^6bits/sec
87380 16384 16384 10.00 23841.26
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Cc: Michael Dalton <mwdalton@xxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
---
drivers/net/virtio_net.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 113ee93..5dc0de0 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -305,7 +305,7 @@ static int receive_mergeable(struct receive_queue *rq, struct sk_buff *head_skb)
struct sk_buff *curr_skb = head_skb;
char *buf;
struct page *page;
- int num_buf, len;
+ int num_buf, len, offset;
num_buf = hdr->mhdr.num_buffers;
while (--num_buf) {
@@ -342,9 +342,15 @@ static int receive_mergeable(struct receive_queue *rq, struct sk_buff *head_skb)
head_skb->truesize += MAX_PACKET_LEN;
}
page = virt_to_head_page(buf);
- skb_add_rx_frag(curr_skb, num_skb_frags, page,
- buf - (char *)page_address(page), len,
- MAX_PACKET_LEN);
+ offset = buf - (char *)page_address(page);
+ if (skb_can_coalesce(curr_skb, num_skb_frags, page, offset)) {
+ skb_coalesce_rx_frag(curr_skb, num_skb_frags - 1,
+ len, MAX_PACKET_LEN);
+ } else {
+ skb_add_rx_frag(curr_skb, num_skb_frags, page,
+ offset, len,
+ MAX_PACKET_LEN);
+ }
--rq->num;
}
return 0;
--
1.8.1.2
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