On 11/16/2016 02:40 PM, Jesper Dangaard Brouer wrote:
On Wed, 16 Nov 2016 09:46:37 -0800
Rick Jones <rick.jon...@hpe.com> wrote:
It is a wild guess, but does setting SO_DONTROUTE affect whether or not
a connect() would have the desired effect? That is there to protect
people from themselves (long story about people using UDP_STREAM to
stress improperly air-gapped systems during link up/down testing....)
It can be disabled with a test-specific -R 1 option, so your netperf
command would become:
netperf -H 198.18.50.1 -t UDP_STREAM -l 120 -- -m 1472 -n -N -R 1
Using -R 1 does not seem to help remove __ip_select_ident()
Bummer. It was a wild guess anyway, since I was seeing a connect() call
on the data socket.
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
Well, the next step I suppose is to have you try a quick netperf
UDP_STREAM under strace to see if your netperf binary does what mine did:
strace -v -o /tmp/netperf.strace netperf -H 198.18.50.1 -t UDP_STREAM -l
1 -- -m 1472 -n -N -R 1
And see if you see the connect() I saw. (Note, I make the runtime 1 second)
rick
