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I was getting specs for dell server and one cpu is an Intel Xeon with 6 cores, another 4 cores. What am I getting with this? Do I need six cores? What does that give me? I don't know what mult-core cpus give me but that's about all I can get.

thanks for any help.

johnny
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  • why would someone vote to close this? – johnny Dec 02 '11 at 17:11
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    Because your question is akin to asking why anyone would need a container ship when there are row boats available. – Sven Dec 02 '11 at 17:18
  • What do you need your server for? – lvella Dec 02 '11 at 17:19
  • these types of questions doesn't fit very well in SO http://blog.stackoverflow.com/2010/11/qa-is-hard-lets-go-shopping/ – Mascarpone Dec 02 '11 at 17:19
  • try to rephrase this question as: what are the benefits of having more cores on a server? – Mascarpone Dec 02 '11 at 17:20
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    If you're shopping for servers and you don't know what the benefits of multiple cores are, you shouldn't be the one shopping for servers. – MDMarra Dec 02 '11 at 17:26
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    Sorry to not be in the club. I will refrain from asking basic questions so as not to bother the elite. I had a genuine question about what a multi-core cpu is for, not what server to buy. Mascarpone has the best solution, better question wording. – johnny Dec 02 '11 at 17:31
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    @johnny This is a site for **professional** systems administrators, per the [faq]. Asking how multiple cores work is a fundamental computing questions, and as such, is not a good fit for this site. – MDMarra Dec 02 '11 at 17:32

3 Answers3

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You can consider a 6 core CPU as six independent CPUs, which will have up to 6 times the computing power than a single CPU.

What you really get out of it is highly dependent of what you want to do with this server. Some workloads don't benefit at all from multicore systems, others really need them to perform acceptable. All in all, a general file/web/mail server will nearly always benefit from more CPUs, but to a varying degree.

In short: It depends.

Sven
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  • I thought you had to have software that took advantage of the other cores. Does Windows automatically use the multi-cores or is this a function of how the motherboard processes data? It splits it up or runs concurrent... – johnny Dec 02 '11 at 17:18
  • If you have a single core, all task running in a given system will have to compete for computing time, when you have more cores, you will have more time to share. But yes, software will need to take multiprocessing into account to really benefit from it, but most server software does this, unless it's specific purpose will make it unfeasible. – Sven Dec 02 '11 at 17:21
  • @johnny Windows automatically uses multi-cores and even multi processor systems depending on the windows version. For example windows server 2008 can handle more than 256 or 512 hardware threads if I'm not mistaken – Ghita Dec 02 '11 at 17:22
  • @johnny Windows itself will use multiple cores just fine. Each application is different though. Some things, like Exchange, take well to multiple cores. Others, like Firebird backed applications, don't use them at all. – sysadmin1138 Dec 02 '11 at 17:22
  • It has little to do with the motherboard or the operating system: Windows does nothing about it. Roughly speaking, the more cores you have, more processes (i.e. more running programs) you can have simultaneously without interfering with each other (ok, not exactly that, but something like that). – lvella Dec 02 '11 at 17:27
  • thank you all for answering this genuine question I had and not thrashing me like I was above in the question. Apparently some question are too basic to ask on SO Serverfault. – johnny Dec 02 '11 at 17:33
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Whilst i can't fully answer your question, you certainly can use the 'Set Affinity' per process or if you have rendering applications i.e. CAD 3D rendering or graphic modelling; it would certainly benefit from multiple core CPUs.

In a very general point of view, the more cores, the faster the application runs (of course the program must have been designed to handle multi-core processing).

Cold T
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A multiple core cpu is like having multiple cpu's on a single motherboard. What multi-core cpu's give you depend on what you are running... it's a matter of will you be running any software on the server that takes advantage of the multiple cores?

Where multi-core cpu's are immensely helpful is where you are running an application that is written to take advantage of them; that is, specifically, multi-threaded applications. Many (perhaps most) legacy apps were written for a single cpu model, so for these it makes little or no difference.

But an app written as a multi-threaded app will be able to take full advantage of those extra cores. As an example, we run an app that used to be single-threaded. It was modified by our programmers to be multi-threaded, and it now runs almost 20x faster on our dual xeon, 24 core dell (each xeon has six physical core, and each is "hyper-threaded", making for 12 logical cores.

Another potential area where multi-core cpu's could be immensely advantageous is where you are running virtual machines. I know that Vmware lets you assign one or more cores to each virtual machine; in these cases, the performance can increase linearly, depending on the application. If the app is i/o bound, multiple cores will still help, but not to the same extent as when it is cpu bound.

PaeneInsula
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