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Running CHR as CAPsMAN on KVM - virtio, e1000 bug

Mon May 20, 2019 10:28 pm

I've noticed that there might be a bug in virtio vNIC support in CHR 6.44.3 (and probably other versions as well). I've been able to replicate the issue as I deployed a test CHR in Centos 7 (QEMU emulator version 2.12.0 (qemu-kvm-ev-2.12.0-18.el7_6.3.1)) with CAPsMAN, and RB951-2n's wlan1 as CAP.

In case of using local-fowarding=yes in datapath everything seems to work okay, but when local-forwarding is disabled, clients complain as uploads don't seem to work at all as seen on the following speedtests

I can mitigate the issue using rtl8139 instead of virtio, but it only supports 100Mbps, and CPU utilization according to tool profile is worse than expected (~40-60% of cpu0/ethernet for one client at about 40Mbps of download), and using e1000 doesn't work for me in production environment as I have 9 ethernets connected to CHR VM, and traffic is only seen on some ethernets but not all.

Can someone using KVM virtualization redo the test with CHR/CAPsMAN deployed with virtio networking?
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Re: Running CHR as CAPsMAN on KVM - virtio, e1000 bug

Mon Jun 24, 2019 1:55 pm

virtio networking seems to be (slightly) broken in many linux kernel versions (including the latest 4.9) ... I've had my share of problems running "normal" linux and I've given up - I moved to use e1000-type of virtual NIC in my VMs.

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