On Tue, Mar 21, 2017 at 8:14 PM, FERNANDO FREDIANI < fernando.fredi...@upx.com> wrote:
> Hello Yaniv. > > Have a new information about this scenario: I have load-balanced the > requests between both vNICs, so each is receiving/sending half of the > traffic in average and the packet loss although it still exists it lowered > to 1% - 2% (which was expected as the CPU to process this traffic is shared > by more than one CPU at a time). > However the Load on the VM is still high probably due to the interrupts. > > Find below in-line the answers to some of your points: > > On 21/03/2017 12:31, Yaniv Kaul wrote: > > > So there are 2 NUMA nodes on the host? And where are the NICs located? > > Tried to search how to check it but couldn't find how. Could you give me a > hint ? > I believe 'lspci -vmm' should provide you with node information per PCI device. 'numactl' can also provide interesting information. > > > BTW, since those are virtual interfaces, why do you need two on the same > VLAN? > > Very good question. It's because of an specific situation where I need to > 2 MAC addresses in order to balance the traffic in LAG in a switch which > does only layer 2 hashing. > > > Are you using hyper-threading on the host? Otherwise, I'm not sure threads > per core would help. > > Yes I have hyper-threading enabled on the Host. Is it worth to enable it ? > Depends on the workload. Some benefit from it, some don't. I wouldn't in your case (it benefits mainly the case of many VMs with small number of vCPUs). Y. > > > Thanks > Fernando > > >> On 18/03/2017 12:53, Yaniv Kaul wrote: >> >> >> >> On Fri, Mar 17, 2017 at 6:11 PM, FERNANDO FREDIANI < >> fernando.fredi...@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/wik >>> i/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/pag >>> e/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 >>> >>> >>> >>> _______________________________________________ >>> Users mailing list >>> Users@ovirt.org >>> http://lists.ovirt.org/mailman/listinfo/users >>> >>> >> >> >> >> > >
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