[ovs-discuss] Xen/OVS - VLAN offloading
Eugene Istomin
e.istomin at edss.ee
Fri May 31 09:55:58 UTC 2013
Thank you,
i will continue this discussion in xen maillists.
--
*/Best regards,/*
/Eugene Istomin/
> On Fri, May 31, 2013 at 5:17 PM, Eugene Istomin <e.istomin at edss.ee>
wrote:
> >> This is dependent on the hypervisor and not being restricted by OVS.
> >> However, the direct benefits of vlan offloading are very minimal and
> >> are really only useful in relation to enabling other offloads.
> >
> > In my testbed results are not minimal (untagged by OVS have ~2 times
more
> > bandwith than untagged by VM)
> >
> > All interfaces have MTU=9000
> >
> >
> > 1)untagged by VM interface (in OVS like "trunks: [1002]")
> >
> > #atop from VM
> > NET | transport | tcpi 22733 | tcpo 80191 | udpi 0 | udpo
> > 4 | NET | eth0 ---- | pcki 22736 | pcko 80243 | si 12 Mbps |
> > so 5777 Mbps | NET | vlan100 ---- | pcki 22738 | pcko 80245 | si
9495
> > Kbps | so 5775 Mbps |
> >
> > #atop from Dom0
> > CPU | sys 57% | irq 39%
> > cpu | sys 58% | irq 41%
> > ..
> > NET | vif1.0 ---- | pcki 227727 | pcko 797502 | si 10 Mbps | so
> > 5743 Mbps NET | vif2.0 ---- | pcki 797748 | pcko 227717 | si 5736
> > Mbps | so 12 Mbps
> >
> >
> >
> > 2) untagged by OVS interface (in OVS like "tag: 1002")
> > #atop from VM - untagged by OVS interface
> > NET | transport | tcpi 8495 | tcpo 163131 | udpi 0 | udpo
> > 0 NET | eth1 ---- | pcki 8495 | pcko 24718 | si 4485 Kbps | so
> > 11 Gbps
> >
> > #atop from Dom0
> > CPU | sys 96% | irq 4%
> > cpu | sys 96% | irq 4%
> > ..
> > NET | vif1.1 ---- | pcki 75974 | pcko 247608 | si 3160 Kbps | so
> > 11 Gbps NET | vif2.1 ---- | pcki 247616 | pcko 75971 | si 11 Gbps
> > | so 4011 Kbps
> >
> >
> > As you can see second variant have full netback sys load in DOM0.
Second
> > have high number of irq and high numbers of pcki/pcko.
> > Is this behavior correct?
>
> You are seeing the result of TSO not functioning in the presence of
> vlans. This is one of the other offloads that I was referring to
> before but it's not directly the result of the features that you
> showed. Regardless, this is a limitation of Xen and not something that
> OVS affects.
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