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net: pktgen: packet bursting via skb->xmit_more

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This patch demonstrates the effect of delaying update of HW tailptr.
(based on earlier patch by Jesper)

burst=1 is the default. It sends one packet with xmit_more=false
burst=2 sends one packet with xmit_more=true and
        2nd copy of the same packet with xmit_more=false
burst=3 sends two copies of the same packet with xmit_more=true and
        3rd copy with xmit_more=false

Performance with ixgbe (usec 30):
burst=1  tx:9.2 Mpps
burst=2  tx:13.5 Mpps
burst=3  tx:14.5 Mpps full 10G line rate

Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov 2014-09-30 17:53:21 -07:00 • committed by David S. Miller
commit 38b2cf2982
2 changed files with 27 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

3
Documentation/networking/pktgen.txt
View file

@ -99,6 +99,9 @@ Examples:
pgset "clone_skb 1" sets the number of copies of the same packet
pgset "clone_skb 0" use single SKB for all transmits
pgset "burst 8" uses xmit_more API to queue 8 copies of the same
packet and update HW tx queue tail pointer once.
"burst 1" is the default
pgset "pkt_size 9014" sets packet size to 9014
pgset "frags 5" packet will consist of 5 fragments
pgset "count 200000" sets number of packets to send, set to zero

26
net/core/pktgen.c
View file

@ -387,6 +387,7 @@ struct pktgen_dev {
u16 queue_map_min;
u16 queue_map_max;
__u32 skb_priority; /* skb priority field */
unsigned int burst; /* number of duplicated packets to burst */
int node; /* Memory node */
#ifdef CONFIG_XFRM
@ -613,6 +614,9 @@ static int pktgen_if_show(struct seq_file *seq, void *v)
if (pkt_dev->traffic_class)
seq_printf(seq, " traffic_class: 0x%02x\n", pkt_dev->traffic_class);
if (pkt_dev->burst > 1)
seq_printf(seq, " burst: %d\n", pkt_dev->burst);
if (pkt_dev->node >= 0)
seq_printf(seq, " node: %d\n", pkt_dev->node);
@ -1124,6 +1128,16 @@ static ssize_t pktgen_if_write(struct file *file,
pkt_dev->dst_mac_count);
return count;
}
if (!strcmp(name, "burst")) {
len = num_arg(&user_buffer[i], 10, &value);
if (len < 0)
return len;
i += len;
pkt_dev->burst = value < 1 ? 1 : value;
sprintf(pg_result, "OK: burst=%d", pkt_dev->burst);
return count;
}
if (!strcmp(name, "node")) {
len = num_arg(&user_buffer[i], 10, &value);
if (len < 0)
@ -3297,6 +3311,7 @@ static void pktgen_wait_for_skb(struct pktgen_dev *pkt_dev)
static void pktgen_xmit(struct pktgen_dev *pkt_dev)
{
unsigned int burst = ACCESS_ONCE(pkt_dev->burst);
struct net_device *odev = pkt_dev->odev;
struct netdev_queue *txq;
int ret;
@ -3347,8 +3362,10 @@ static void pktgen_xmit(struct pktgen_dev *pkt_dev)
pkt_dev->last_ok = 0;
goto unlock;
}
atomic_inc(&(pkt_dev->skb->users));
ret = netdev_start_xmit(pkt_dev->skb, odev, txq, false);
atomic_add(burst, &pkt_dev->skb->users);
xmit_more:
ret = netdev_start_xmit(pkt_dev->skb, odev, txq, --burst > 0);
switch (ret) {
case NETDEV_TX_OK:
@ -3356,6 +3373,8 @@ static void pktgen_xmit(struct pktgen_dev *pkt_dev)
pkt_dev->sofar++;
pkt_dev->seq_num++;
pkt_dev->tx_bytes += pkt_dev->last_pkt_size;
if (burst > 0 && !netif_xmit_frozen_or_drv_stopped(txq))
goto xmit_more;
break;
case NET_XMIT_DROP:
case NET_XMIT_CN:
@ -3374,6 +3393,8 @@ static void pktgen_xmit(struct pktgen_dev *pkt_dev)
atomic_dec(&(pkt_dev->skb->users));
pkt_dev->last_ok = 0;
}
if (unlikely(burst))
atomic_sub(burst, &pkt_dev->skb->users);
unlock:
HARD_TX_UNLOCK(odev, txq);
@ -3572,6 +3593,7 @@ static int pktgen_add_device(struct pktgen_thread *t, const char *ifname)
pkt_dev->svlan_p = 0;
pkt_dev->svlan_cfi = 0;
pkt_dev->svlan_id = 0xffff;
pkt_dev->burst = 1;
pkt_dev->node = -1;
err = pktgen_setup_dev(t->net, pkt_dev, ifname);