Irqbalance, which is enabled by default in later releases, tries to set up interrupts on VCPUs that are already busy, but not too busy. The tool xenpm get-cpu-topology is useful here for obtaining CPU topology of the host.įew fast VIFs For a particular host, if the number of VM network connections (VIFs) that are required to be fast is less than around 2/3 of netback threads in dom0, a further performance boost can be achieved for such connections. In the scenario described, we could pin the control domain VCPUs to the first four PCPUs, and the VM's VCPU to the fifth PCPU if we installed any more VMs for which network performance is not critical, we can easily pin them to the second node, i.e. The pinning should be performed before the VM starts, using vcpu-params:mask - see for more information. Therefore, in scenarios where network performance is of great importance, we should pin VCPUs of the control domain and any user domains explicitly, and close-by in terms of NUMA-ness. The VM will be put on a different CPU node than the control domain, which means that the communication between the VM's netfront and the control domain's netback will not be efficient. For example, suppose we have a 2-node host, each with 12 logical CPUs (Physical CPUs/PCPUs), and we install a single 1-VCPU VM. However, as explained above, this rule is not great for network performance. In general, this is a good rule, since each VM then has a large cache, and cache-misses are minimised. Moreover, Xen Scheduler prefers to put all VMs (including the control domain) as far away from each other in terms of NUMA-ness as possible. Similarly, VCPUs of any VM installed will be (by default) randomly allocated to most-free PCPUs. By default, the control domain uses 4 VCPUs, which are mapped to 4 (by default randomly-chosen) PCPUs.

It is expected that this will be made much easier in future versions of the product. Chiranjeevi Medha Spoken English Videos Free Download. At the moment, it is not easy to determine what netback a netfront is linked to - this can, for example, be done by sending some traffic over netfront and observing which netback is being used (by looking at top in the control domain).

As was mentioned before, a netfront is currently allocated in a round-robin fashion to available netbacks.

Netperf for windows