Vlad,
commit 6acf54f1cf0a6747bac9fea26f34cfc5a9029523
macvtap: Add support of packet capture on macvtap device.
causes a performance regression for iperf traffic between two KVM guests
on my s390 system. Both guests are connected via two macvtaps on the same OSA
network card.
Before that patch I get ~20 Gbit/sec between two guests, afterwards I get
~4Gbit/sec
Latency seems to be unchanges (uperf 1byte ping pong).
According to ifconfig in the guest, I have ~ 1500 bytes per packet with this
patch and ~ 40000 bytes without. So for some reason this patch causes the
network stack to do segmentation. (the guest kernel stays the same, only host
kernel is changed).
Any ideas?
Christian
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