[ovs-dev] vlan tag add/remove affect bandwidth a lot

[Jesse Gross]

On Fri, Oct 18, 2013 at 12:08 AM, Li, Chen <chen.li at intel.com> wrote:

>  I have changed my test method a little to make the issue more clear:****
>
> ********
>
> ** **
>
> As you can see, my vm has two virtual NIC, tap1 is working under VLAN
> (tag=2002), while tap2 is working under FLAT. ****
>
> And the bandwidth is :****
>
> Test Node => tap1   2.85 Gbits/sec****
>
> Test Node => tap2   9.40 Gbits/sec****
>
> ** **
>
> Flows rules applied:****
>
> ovs-ofctl dump-flows br-int****
>
> NXST_FLOW reply (xid=0x4):****
>
> cookie=0x0, duration=2024.067s, table=0, n_packets=989820,
> n_bytes=23566560107, idle_age=1, priority=3,in_port=16,*vlan_tci=0x0000
> actions=mod_vlan_vid:2*,NORMAL****
>
> cookie=0x0, duration=2024.769s, table=0, n_packets=4873950,
> n_bytes=7378336782, idle_age=20, priority=3,in_port=17,*dl_vlan=2002
> actions=mod_vlan_vid:1*,NORMAL****
>
> cookie=0x0, duration=2029.604s, table=0, n_packets=52, n_bytes=3768,
> idle_age=72, priority=2,in_port=16 actions=drop****
>
> cookie=0x0, duration=2027.391s, table=0, n_packets=4729, n_bytes=286686,
> idle_age=1, priority=2,in_port=17 actions=drop****
>
> cookie=0x0, duration=2031.156s, table=0, n_packets=3161368,
> n_bytes=208726297, idle_age=20, priority=1 actions=NORMAL****
>
> ** **
>
> ovs-ofctl dump-flows br-eth4****
>
> NXST_FLOW reply (xid=0x4):****
>
> cookie=0x0, duration=2043.307s, table=0, n_packets=925503,
> n_bytes=61092489, idle_age=90, priority=4,in_port=7,*dl_vlan=2
> actions=strip_vlan*,NORMAL****
>
> cookie=0x0, duration=2048.566s, table=0, n_packets=47, n_bytes=3212,
> idle_age=91, priority=2,in_port=7 actions=drop****
>
> cookie=0x0, duration=2049.988s, table=0, n_packets=989979,
> n_bytes=23566580239, idle_age=1, priority=1 actions=NORMAL****
>
> ** **
>
> ovs-ofctl dump-flows br-eth5****
>
> NXST_FLOW reply (xid=0x4):****
>
> cookie=0x0, duration=2047.936s, table=0, n_packets=2235861,
> n_bytes=147635900, idle_age=43, priority=4,in_port=4,*dl_vlan=1
> actions=mod_vlan_vid:2002*,NORMAL****
>
> cookie=0x0, duration=2050.289s, table=0, n_packets=4784, n_bytes=293458,
> idle_age=1, priority=2,in_port=4 actions=drop****
>
> cookie=0x0, duration=2051.95s, table=0, n_packets=305743,
> n_bytes=7076819244, idle_age=1, priority=1 actions=NORMAL****
>
> ** **
>
> Both path has an adding and stripping of VLAN tags operation, so where
> can I find the difference from code ??
>

The problem is almost certainly not the actual modification of tags but in
the interactions with the rest of the system. In that case, it's not
surprising that rewriting the tags doesn't change anything.
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