Re: [PATCH net-next] hv_netvsc: Use simple parser for IPv4 and v6 headers

From: Sergei Shtylyov
Date: Wed Dec 16 2015 - 13:45:34 EST


On 12/16/2015 09:34 PM, Sergei Shtylyov wrote:

To avoid performance overhead when using skb_flow_dissect_flow_keys(),
we switch to the simple parsers to get the IP and port numbers.

Performance comparison: throughput (Gbps):
Number of connections, before patch, after patch
1 8.56 10.18
4 11.17 14.07
16 12.21 21.78
64 18.71 32.08
256 15.92 26.32
1024 8.41 15.49
3000 7.82 11.58

Signed-off-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
Tested-by: Simon Xiao <sixiao@xxxxxxxxxxxxx>
Reviewed-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
---
drivers/net/hyperv/netvsc_drv.c | 38 +++++++++++++++++++++++++++++---------
1 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 1c8db9a..e28951f 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -237,20 +237,40 @@ static u32 comp_hash(u8 *key, int klen, void *data,
int dlen)
[...]
+ if (iphdr->version == 4) {
+ dbuf[0] = iphdr->saddr;
+ dbuf[1] = iphdr->daddr;
+ if (iphdr->protocol == IPPROTO_TCP) {
+ dbuf[2] = *(__be32 *)&tcp_hdr(skb)->source;
+ data_len = 12;
+ } else {
+ data_len = 8;
+ }
+ } else if (ipv6hdr->version == 6) {
+ memcpy(dbuf, &ipv6hdr->saddr, 32);
+ if (ipv6hdr->nexthdr == IPPROTO_TCP) {
+ dbuf[8] = *(__be32 *)&tcp_hdr(skb)->source;
+ data_len = 36;
+ } else {
+ data_len = 32;
+ }
+ } else {
+ return false;
+ }

This is asking to be a *switch* statement.

Oops, nevermind. I'd misread the code.

[...]

MBR, Sergei

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