On Fri, Mar 17, 2017 at 6:11 PM, FERNANDO FREDIANI < fernando.frediani@upx.com> wrote:
Hello all.
I have a peculiar problem here which perhaps others may have had or know about and can advise.
I have Virtual Machine with 2 VirtIO NICs. This VM serves around 1Gbps of traffic with thousands of clients connecting to it. When I do a packet loss test to the IP pinned to NIC1 it varies from 3% to 10% of packet loss. When I run the same test on NIC2 the packet loss is consistently 0%.
From what I gather I may have something to do with possible lack of Multi Queu VirtIO where NIC1 is managed by a single CPU which might be hitting 100% and causing this packet loss.
Looking at this reference (https://fedoraproject.org/ wiki/Features/MQ_virtio_net) I see one way to test it is start the VM with 4 queues (for example), but checking on the qemu-kvm process I don't see option present. Any way I can force it from the Engine ?
I don't see a need for multi-queue for 1Gbps. Can you share the host statistics, the network configuration, the qemu-kvm command line, etc.? What is the difference between NIC1 and NIC2, in the way they are connected to the outside world?
This other reference (https://www.linux-kvm.org/page/Multiqueue#Enable_MQ_ feature) points to the same direction about starting the VM with queues=N
Also trying to increase the TX ring buffer within the guest with ethtool -g eth0 is not possible.
Oh, by the way, the Load on the VM is significantly high despite the CPU usage isn't above 50% - 60% in average.
Load = latest 'top' results? Vs. CPU usage? Can mean a lot of processes waiting for CPU and doing very little - typical for web servers, for example. What is occupying the CPU? Y.
Thanks Fernando
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