On Wed, 2016-11-16 at 23:40 +0100, Jesper Dangaard Brouer wrote:
> Using -R 1 does not seem to help remove __ip_select_ident()
>
> Samples: 56K of event 'cycles', Event count (approx.): 78628132661
> Overhead Command Shared Object Symbol
> + 9.11% netperf [kernel.vmlinux] [k] __ip_select_ident
> + 6.98% netperf [kernel.vmlinux] [k] _raw_spin_lock
> + 6.21% swapper [mlx5_core] [k] mlx5e_poll_tx_cq
> + 5.03% netperf [kernel.vmlinux] [k]
> copy_user_enhanced_fast_string
> + 4.69% netperf [kernel.vmlinux] [k] __ip_make_skb
> + 4.63% netperf [kernel.vmlinux] [k] skb_set_owner_w
> + 4.15% swapper [kernel.vmlinux] [k] __slab_free
> + 3.80% netperf [mlx5_core] [k] mlx5e_sq_xmit
> + 2.00% swapper [kernel.vmlinux] [k] sock_wfree
> + 1.94% netperf netperf [.] send_data
> + 1.92% netperf netperf [.] send_omni_inner
Check "ss -nu" ?
You will see if sockets are connected (present in ss output or not)
UDP being connected does not prevent __ip_select_ident() being used.
if ((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) {
So you need IP_DF being set, and skb->ignore_df being 0
-> time to try IP_MTU_DISCOVER ;)
