On Thu, 2016-11-17 at 19:30 +0100, Jesper Dangaard Brouer wrote:
> The point is I can see a socket Send-Q forming, thus we do know the
> application have something to send. Thus, and possibility for
> non-opportunistic bulking. Allowing/implementing bulk enqueue from
> socket layer into qdisc layer, should be fairly simple (and rest of
> xmit_more is already in place).
As I said, you are fooled by TX completions.
Please make sure to increase the sndbuf limits !
echo 2129920 >/proc/sys/net/core/wmem_default
lpaa23:~# sar -n DEV 1 10|grep eth1
10:49:25 eth1 7.00 9273283.00 0.61 2187214.90 0.00
0.00 0.00
10:49:26 eth1 1.00 9230795.00 0.06 2176787.57 0.00
0.00 1.00
10:49:27 eth1 2.00 9247906.00 0.17 2180915.45 0.00
0.00 0.00
10:49:28 eth1 3.00 9246542.00 0.23 2180790.38 0.00
0.00 1.00
10:49:29 eth1 1.00 9239218.00 0.06 2179044.83 0.00
0.00 0.00
10:49:30 eth1 3.00 9248775.00 0.23 2181257.84 0.00
0.00 1.00
10:49:31 eth1 4.00 9225471.00 0.65 2175772.75 0.00
0.00 0.00
10:49:32 eth1 2.00 9253536.00 0.33 2182666.44 0.00
0.00 1.00
10:49:33 eth1 1.00 9265900.00 0.06 2185598.40 0.00
0.00 0.00
10:49:34 eth1 1.00 6949031.00 0.06 1638889.63 0.00
0.00 1.00
Average: eth1 2.50 9018045.70 0.25 2126893.82 0.00
0.00 0.50
lpaa23:~# ethtool -S eth1|grep more; sleep 1;ethtool -S eth1|grep more
xmit_more: 2251366909
xmit_more: 2256011392
lpaa23:~# echo 2256011392-2251366909 | bc
4644483
PerfTop: 76969 irqs/sec kernel:96.6% exact: 100.0% [4000Hz cycles:pp],
(all, 48 CPUs)
---------------------------------------------------------------------------------------------------------------------------------------------------------------
11.64% [kernel] [k] skb_set_owner_w
6.21% [kernel] [k] queued_spin_lock_slowpath
4.76% [kernel] [k] _raw_spin_lock
4.40% [kernel] [k] __ip_make_skb
3.10% [kernel] [k] sock_wfree
2.87% [kernel] [k] ipt_do_table
2.76% [kernel] [k] fq_dequeue
2.71% [kernel] [k] mlx4_en_xmit
2.50% [kernel] [k] __dev_queue_xmit
2.29% [kernel] [k] __ip_append_data.isra.40
2.28% [kernel] [k] udp_sendmsg
2.01% [kernel] [k] __alloc_skb
1.90% [kernel] [k] napi_consume_skb
1.63% [kernel] [k] udp_send_skb
1.62% [kernel] [k] skb_release_data
1.62% [kernel] [k] entry_SYSCALL_64_fastpath
1.56% [kernel] [k] dev_hard_start_xmit
1.55% udpsnd [.] __libc_send
1.48% [kernel] [k] netif_skb_features
1.42% [kernel] [k] __qdisc_run
1.35% [kernel] [k] sk_dst_check
1.33% [kernel] [k] sock_def_write_space
1.30% [kernel] [k] kmem_cache_alloc_node_trace
1.29% [kernel] [k] __local_bh_enable_ip
1.21% [kernel] [k] copy_user_enhanced_fast_string
1.08% [kernel] [k] __kmalloc_reserve.isra.40
1.08% [kernel] [k] SYSC_sendto
1.07% [kernel] [k] kmem_cache_alloc_node
0.95% [kernel] [k] ip_finish_output2
0.95% [kernel] [k] ktime_get
0.91% [kernel] [k] validate_xmit_skb
0.88% [kernel] [k] sock_alloc_send_pskb
0.82% [kernel] [k] sock_sendmsg
