Using Scheduler Operation with CPU Affinity

The definition and understanding of the technology “CPU Pinning” or very precisely “CPU Affinity” has been distorted and confused over the last decade.  This knowledge base blog serves to clarify, the realized distortions and misunderstandings. 

This is specifically pivotal now as the desire on the part of several customers and partners to create optimized sub-capacity architectures, most of the time for reasons pertaining to 3rd party software licensing has never been stronger enough to become an adorable support. 

Scheduler operation while utilizing CPU Affinity (2145719) : To provides  an enhanced information on scheduler operation while using CPU affinity some resolutions are observed.

By mentioning a CPU affinity setting and configuration for virtual machines, you might restrict the assignment of virtual machines to a subset of the available processors in multiprocessor systems.

The scheduler operation warranties that virtual CPUs are not moved to or execute on a processor outside the configured affinity set.  Such behavior is consistent throughout all the present versions of  ESXi.

Other virtual machine worlds, present outside the virtual CPUs where guest operating system application binaries are executed, might include threads to perform processing needed for emulating mouse, screen, keyboard, CD-ROM, miscellaneous legacy devices and IO completion for the virtual machine.

The CPU affinity setting for a virtual machine is applicable to all of the virtual CPUs related with the virtual machine.

Such demark of physical boundaries by the scheduler might required for some guest application licensing models.

By utilizing this feature, you may allot each virtual machine to processors in the mentioned affinity set. In context to this, the term CPU depicts to a logical processor on a hyperthreaded system and indicates to a core on a non-hyper threaded system.

CPU affinity mentions virtual machine-to-processor placement constraints and which is variant from the relationship created by a Virtual Machine to Virtual Machine or Virtual Machine to Host affinity rule that specifies Virtual Machine-Virtual Machine host placement constraints.