mirror/xdp-project-bpf-examples
1
0
Fork 0
mirror of https://github.com/xdp-project/bpf-examples.git synced 2024-05-06 15:54:53 +00:00
Code Issues Projects Releases Wiki Activity

traffic-pacing-edt: New strategy: Shape at MAC layer with Ethernet

Browse Source 
Take into account MAC layer overhead per packet.

Signed-off-by: Jesper D. Brouer <netoptimizer@brouer.com>
This commit is contained in:
Jesper D. Brouer
2020-11-21 15:57:14 +01:00
parent 6b5648158b
commit 794c074d7d
1 changed files with 41 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

45
traffic-pacing-edt/edt_pacer02.c
View File

@@ -11,19 +11,50 @@ char _license[] SEC("license") = "GPL";
#define NS_PER_SEC 1000000000
//#define RATE_IN_BITS (1000 * 1000 * 1000ULL)
//#define RATE_IN_BITS (998 * 1000 * 1000ULL)
/* Test different rates in production machine, and measure iperf3 TCP-goodput */
//#define RATE_IN_BITS (800 * 1000 * 1000ULL)// prod: 765 Mbits/sec (stable)
//#define RATE_IN_BITS (900 * 1000 * 1000ULL)// prod: 861 Mbits/sec (stable)
//#define RATE_IN_BITS (950 * 1000 * 1000ULL)// prod: 908 Mbits/sec (stable)
///#define RATE_IN_BITS (950 * 1000 * 1000ULL)// prod: 908 Mbits/sec (stable)
//#define RATE_IN_BITS (960 * 1000 * 1000ULL)// prod: 918 Mbits/sec
#define RATE_IN_BITS (970 * 1000 * 1000ULL)// prod: 928 Mbits/sec
//#define RATE_IN_BITS (970 * 1000 * 1000ULL)// prod: 928 Mbits/sec
//#define RATE_IN_BITS (980 * 1000 * 1000ULL)// prod: 920 Mbits/sec (unstable)
//#define RATE_IN_BITS (990 * 1000 * 1000ULL)// prod: 920 Mbits/sec (unstable)
//#define RATE_IN_BITS (999 * 1000 * 1000ULL)// prod: (unstable)
/* Per packet overhead: two VLAN headers == 8 bytes
*
* skb->wire_len doesn't seem to take the two VLAN headers into
* account. Loading BPF-prog on VLAN net_device is can only see 1
* VLAN, and this is likely HW offloaded into skb->vlan.
*/
//#define OVERHEAD (8)
/* New strategy: Shape at MAC (Medium Access Control) layer with Ethernet
*
* Production use-case is pacing traffic at 1Gbit/s wirespeed, using a
* 10Gbit/s NIC, because 1G end-user switch cannot handle bursts.
*
* (https://en.wikipedia.org/wiki/Interpacket_gap
* 12 bytes = interframe gap (IFG) 96 bit
* (https://en.wikipedia.org/wiki/Ethernet_frame)
* 8 bytes = MAC preamble
* 4 bytes = Ethernet Frame Check Sequence (FCS) CRC
* 46 bytes = Minimum Payload size
*
* 14 bytes = Ethernet header
* 8 bytes = 2x VLAN headers
*/
//#define RATE_IN_BITS (1000 * 1000 * 1000ULL) /* Full 1Gbit/s */
//#define RATE_IN_BITS (990 * 1000 * 1000ULL)
#define RATE_IN_BITS (950 * 1000 * 1000ULL)
#define OVERHEAD (12 + 8 + 4 + 8) /* 14 already in wire_len */
//#define OVERHEAD (12 + 8 + 4) /* 14 already in wire_len */
#define ETH_MIN (84)
/* skb->len in bytes, thus easier to keep rate in bytes */
#define RATE_IN_BYTES (RATE_IN_BITS / 8)
@@ -59,6 +90,7 @@ static __always_inline int sched_departure(struct __sk_buff *skb)
struct edt_val *edt;
__u64 t_queue_sz;
__u64 t_xmit_ns;
__u64 wire_len;
__u64 t_next;
__u64 t_curr;
int key = 0;
@@ -75,7 +107,12 @@ static __always_inline int sched_departure(struct __sk_buff *skb)
* added on transmit. Fortunately skb->wire_len at TC-egress hook (not
* ingress) include these headers. (See: qdisc_pkt_len_init())
*/
t_xmit_ns = ((__u64)skb->wire_len) * NS_PER_SEC / RATE_IN_BYTES;
wire_len = skb->wire_len + OVERHEAD;
wire_len = wire_len > ETH_MIN ? wire_len : ETH_MIN;
t_xmit_ns = (wire_len) * NS_PER_SEC / RATE_IN_BYTES;
// t_xmit_ns = ((__u64)skb->wire_len) * NS_PER_SEC / RATE_IN_BYTES;
// t_xmit_ns = ((__u64)skb->wire_len) * NS_PER_SEC / edt->rate;
now = bpf_ktime_get_ns();