@
myliyifei 经验，文档应该也有的吧，但是首先要确定你自己要跑什么服务，你拿它来做存储服务的话CPU当然不要紧，vCPU本来就一直处于Idle状态，不需要调配。 如果是CPU要求高的服务那这个cache对性能影响很关键。
随便找了一个
http://www.vmware.com/files/pdf/techpaper/VMware-vSphere-CPU-Sched-Perf.pdf----------------------------
Load Balancing
ESXi is typically deployed on multiprocessor systems. On multiprocessor systems, balancing CPU load across
processors, or load balancing, is critical to the performance. Load balancing is achieved by having a world migrate
from a busy pCPU to a less loaded pCPU. Generally, the world migration improves the responsiveness of a system
and its overall CPU utilization.
Consider a system that has only two pCPUs, where a number of worlds are ready to run on one pCPU while none
on the other. Without load balancing, such imbalance would persist. As a result, the ready worlds accrue
unnecessary scheduling latency and the CPU utilization becomes only half of what could be attainable.
On ESXi, the world migration can be initiated by either a pCPU, which becomes idle, or a world, which becomes
ready to be scheduled. The former is also referred to as pull migration while the latter is referred to as push
migration. With these migration policies, ESXi achieves high utilization and low scheduling latency.
The cost of world migration is also carefully evaluated when making a migration decision. When a world migrates
away from the source pCPU, where it has run awhile and brought instructions and data (the working set*
) into the
on-chip cache, the world has to bring the working set back into the cache†
of the destination pCPU. For a
workload that benefits from caching, frequent migrations can be detrimental.
There are many other factors that need to be considered to make optimal scheduling decision. In vSphere 5.x, the
goodness load balancing algorithm is introduced.