VMware Cloud Community
korba
Contributor
Contributor
Jump to solution

Managing Cores

Trying to switch to VMWARE the most painless way didn't work. Didn't have a chance to start up ESXi3.5 or ESX 4 on our servers 3*Intel SR1500ALSAS with an active backplane. So we decided to go for Win 2003+VmWare Server 2.0. And after the decision i came up across a post mentioning that only 2 CPU cores per VM are allowed. As there won't be too many CPU hungry applications (WSUS, AV, MSSQL, local ERP, some Informix and some nix stuff) that won't be such a problem (i hope). But how does Server 2 balance all the cores itself? We have 2xeon on each machine, so that makes it 8 cores per place. Will it put vm1 on cores 1&2, vm2 on cores 3&4 e.t.c?

Reply
0 Kudos
1 Solution

Accepted Solutions
Ken_Cline
Champion
Champion
Jump to solution

The hypervisor will schedule the virtual CPUs (vCPUs) across all available physical cores. With ESX/ESXi, the hypervisor has a great deal of control over this scheduling activity and will try to optimize cache hits and "near" memory utilization. In the hosted products (like VMware Server), the host operating system is ultimately responsible for scheduling processes on the physical cores. So...the vCPUs will (mostly) "stick" to the same pCores; however, it is possible that they will "migrate" from core to core.

The great thing about this virtualization stuff is that you really don't need to worry too much about how it works at the scheduling level - just know that it works and that, if the resources are available on the host, they will be granted to the guest as needed. Obviously, if you seriously overcommit your host resources, your guests can become resource starved.

Ken Cline

VMware vExpert 2009

VMware Communities User Moderator

Blogging at: http://KensVirtualReality.wordpress.com/

Ken Cline VMware vExpert 2009 VMware Communities User Moderator Blogging at: http://KensVirtualReality.wordpress.com/

View solution in original post

Reply
0 Kudos
1 Reply
Ken_Cline
Champion
Champion
Jump to solution

The hypervisor will schedule the virtual CPUs (vCPUs) across all available physical cores. With ESX/ESXi, the hypervisor has a great deal of control over this scheduling activity and will try to optimize cache hits and "near" memory utilization. In the hosted products (like VMware Server), the host operating system is ultimately responsible for scheduling processes on the physical cores. So...the vCPUs will (mostly) "stick" to the same pCores; however, it is possible that they will "migrate" from core to core.

The great thing about this virtualization stuff is that you really don't need to worry too much about how it works at the scheduling level - just know that it works and that, if the resources are available on the host, they will be granted to the guest as needed. Obviously, if you seriously overcommit your host resources, your guests can become resource starved.

Ken Cline

VMware vExpert 2009

VMware Communities User Moderator

Blogging at: http://KensVirtualReality.wordpress.com/

Ken Cline VMware vExpert 2009 VMware Communities User Moderator Blogging at: http://KensVirtualReality.wordpress.com/
Reply
0 Kudos