3 slow cores or 2 fast cores?

[JACKDRUID]

Been reading quite a few AMD tricore reviews... it seems to me, for the same low price, i could either pick up 3 slow cores or 2 fast cores... which one would you get?

 

[v8envy]

This is a no-brainer. If I need the processing power of > 2 cores, I get a quad -- 25% more processing power for a small increase in total system cost. If I don't, I get either a cheap or a fast dual. Now, if the tri-cores get cheaper than dualies, sure. Why not. Until then why bother?

I have yet to see a case where an application demands a slow tri-core. There are plenty of applications that favor either a fast dual core or a quad.

 

[JACKDRUID]

ya i'm comparing Intel 2 core vs AMD 3-core which cost the same..

seems like intel 2 core is much faster in most cases.. but the extra core does sound attractive lol..

would 3core be faster if i run 3 instances of virtual pc?

 

[v8envy]

Whether you run zero or a hundred virtual machines, the VMs are not what is soaking up (significant) resources. If all the VMs have access to all the cores (hrm. does vmware even support 3x cores?) then whatever runs fastest without a vm will still run fastest with a vm.

What you'd gain with a 3x core is the ability to give each vm only one CPU. In other words, manageability and isolation.

If you're running a lot of VMs and need that kind of control a quad sounds like the perfect solution for you. Price difference between the tri cores and quads is noise when you consider whole system cost, and that spare 25% may come in handy. If you're only running a few lightly loaded VMs you'll be better off with a cheaper dual core.

Leave the tris to the retail shelf consumers. They don't need the performance of either, so both work great for them.

 

[Ratman6161]

Originally posted by: v8envy
Whether you run zero or a hundred virtual machines, the VMs are not what is soaking up (significant) resources. If all the VMs have access to all the cores (hrm. does vmware even support 3x cores?) then whatever runs fastest without a vm will still run fastest with a vm.

What you'd gain with a 3x core is the ability to give each vm only one CPU. In other words, manageability and isolation.

If you're running a lot of VMs and need that kind of control a quad sounds like the perfect solution for you. Price difference between the tri cores and quads is noise when you consider whole system cost, and that spare 25% may come in handy. If you're only running a few lightly loaded VMs you'll be better off with a cheaper dual core.

Leave the tris to the retail shelf consumers. They don't need the performance of either, so both work great for them.

Mmmm. Its not nessesarily tru that virtual machines are not soaking up resources. Just like with a hardware system, it all depends on what those virtual machines are doing.

Do all the virtual machines have access to all the cores? Well, there again, not unnecessarily. Each virtual machine is running as a separate process on the host system. By default each VM has access to all - but you can set the processor affinity separately for each of the running VMs so it is possible to set things up such that different VM's are using different cores. Also, each VM can be set up as at most a 2 cpu system (if you are talking about VMWare Workstation, VMWare Player or VMWare Server). If you have a full blown ESX server setup you can allocate however many cores your guest OS will support. For example, the servers I work with have dual Intel 5345's for a total of 8 cores. The guest OS's I'm using are Windows Server 2003 Standard and I have VM's with as many as 4 cpus and as few as 1 depending on the assigned task.

All that said, if any of this were important to you, you would be going with a quad. The scenarios I can dream up where a tri would have any advantage over a dual are so limited they arent worth thinking about.

 

[v8envy]

Originally posted by: Ratman6161

Mmmm. Its not nessesarily tru that virtual machines are not soaking up resources. Just like with a hardware system, it all depends on what those virtual machines are doing.

Looking at host vs guest page fault rates, interrupts and benchmark results got me 1-5% extra resource use by virtualization with vmware server on a core2 quad as opposed to running the same natively. Sync and async I/O rates were significantly worse for guests, but didn't seem to use much host CPU at all. I was curious, so I ran a bunch of different server-y benchmarks in guest as well as host VMs. I wasn't using snapshots, and had the guest OS access partitions directly. Guest vm process had RAM dedicated to it, no swapping allowed. It might be worse for desktop-y programs I guess. Anything memory/network/CPU heavy was not significantly impacted.

Good to know the ESX flavor lets you manage so well. I'll keep that bit filed away for reference.

 

[JACKDRUID]

Thank you for all your reply.

yes i was running virtual server and it lets you assign 1 core per guest machine... but you are correct, 2 fast core s better anyway.

 

[Ratman6161]

Originally posted by: JACKDRUID
Thank you for all your reply.

yes i was running virtual server and it lets you assign 1 core per guest machine... but you are correct, 2 fast core s better anyway.

I assume you mean Microsoft Virtual Server? When we began looking at virtualization, thats where we looked first because we are primarily a Microsoft Shop and its free. but we quickly discarded it. The main reason was that it will only let you create single cpu virtual machines and we wanted to be able to do up to quads for our VM that hosts our DB server.

I have not had a chance to try out the virtualization support in Windows Server 2008, but I can tell you the previous MS products were just not in the same league as VMWare for a variety of reasons. If you need something free, vmware server is the way to go. It will at least let you do two cpu VM's and is robust enough to use in a production environment.

 

[Ratman6161]

Originally posted by: v8envy


Good to know the ESX flavor lets you manage so well. I'll keep that bit filed away for reference.

Actually you can download the latest version of ESX server. Its just that without a license file what you will have is a 60 day trial, but if you just want to try it out and see what it looks like, that works. Also you can use the free version of VMWare converter to import VM's you have been running on VMWAre server.

The only bad thing is that ESX server will not run on IDE or SATA drives so you cant test it on an old desktop machine. You have to have somthing with SCSI or SAS.

 

[JACKDRUID]

Originally posted by: Ratman6161

Originally posted by: JACKDRUID
Thank you for all your reply.

yes i was running virtual server and it lets you assign 1 core per guest machine... but you are correct, 2 fast core s better anyway.

I assume you mean Microsoft Virtual Server? When we began looking at virtualization, thats where we looked first because we are primarily a Microsoft Shop and its free. but we quickly discarded it. The main reason was that it will only let you create single cpu virtual machines and we wanted to be able to do up to quads for our VM that hosts our DB server.

I have not had a chance to try out the virtualization support in Windows Server 2008, but I can tell you the previous MS products were just not in the same league as VMWare for a variety of reasons. If you need something free, vmware server is the way to go. It will at least let you do two cpu VM's and is robust enough to use in a production environment.

its primarily for home use and testing.. but free is always good
I'll check out vmware tonght. thank you.