11-10-2010
There's no hard rule on this. Some people over commit.. so the sum total of VM resources is greater than actual physical resources. Usually, one place where this is done is with regards to CPUs. BUT... if your VMs REALLY need a whole bunch of CPU resources, it's possible that you'll reach the limits of what you can actually give and have a "good" performing platform. IMHO, it's pretty safe to say that we waste about 50% of CPU resources (in general, the number is usually much, much higher). So you could use that for a very conservative number of total CPUs you can dole out. And don't discount the hyperthreads... they do help out as well...
If your plan is to virtualize large scale servers (e.g. 4 CPUs + 8G+ memory) ... I think that's a BAD plan. Virtualization is most effective when talking about smaller footprint machines. Then the scalability can be VERY large.. and you can really over commit (but again, there is no RULE).
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LEARN ABOUT CENTOS
hwloc_intel_mic_get_device_cpuset
Intel Xeon Phi (MIC) Specific Functions(3) Hardware Locality (hwloc) Intel Xeon Phi (MIC) Specific Functions(3)
NAME
Intel Xeon Phi (MIC) Specific Functions -
Functions
static inline int hwloc_intel_mic_get_device_cpuset (hwloc_topology_t topology , int idx , hwloc_cpuset_t set)
static inline hwloc_obj_t hwloc_intel_mic_get_device_osdev_by_index (hwloc_topology_t topology, unsigned idx)
Detailed Description
Function Documentation
static inline int hwloc_intel_mic_get_device_cpuset (hwloc_topology_t topology, int idx, hwloc_cpuset_tset) [static]
Get the CPU set of logical processors that are physically close to MIC device whose index is idx. Return the CPU set describing the
locality of the MIC device whose index is idx.
Topology topology and device index idx must match the local machine. I/O devices detection is not needed in the topology.
The function only returns the locality of the device. If more information about the device is needed, OS objects should be used instead,
see hwloc_intel_mic_get_device_osdev_by_index().
This function is currently only implemented in a meaningful way for Linux; other systems will simply get a full cpuset.
static inline hwloc_obj_t hwloc_intel_mic_get_device_osdev_by_index (hwloc_topology_ttopology, unsignedidx) [static]
Get the hwloc OS device object corresponding to the MIC device for the given index. Return the OS device object describing the MIC device
whose index is idx. Return NULL if there is none.
The topology topology does not necessarily have to match the current machine. For instance the topology may be an XML import of a remote
host. I/O devices detection must be enabled in the topology.
Note:
The corresponding PCI device object can be obtained by looking at the OS device parent object.
Author
Generated automatically by Doxygen for Hardware Locality (hwloc) from the source code.
Version 1.7 Sun Apr 7 2013 Intel Xeon Phi (MIC) Specific Functions(3)