Re: [CentOS-virt] What are KVM guest cores?
On 11/19/2010 01:43 AM, Ben McGinnes wrote: On 19/11/10 11:01 AM, Kenni Lund wrote: Do you have a rule of thumb as to how many core to assign to a guest? For instance, with an Intel x5650 with 6 real and 12 hyperthreaded cores, how many cores would you assign to the guest? It fully depends on the load of your guests and how many guests you want/need to run on a single server. It also depends on what each guest is doing. Some software, like the Postfix MTA, has issues with the timer in a VM and in circumstances like that you want to minimise the number of cores if you can't skip the use of the VM entirely. Kenni is right, though, test it and see whatever works best for your project. Regards, Ben Thank you! ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] What are KVM guest cores?
On 11/19/2010 02:25 AM, Nick wrote: Therefore, in your given case, think six not twelve. Common advice is to leave one core for the host OS/scheduler. Which leaves you with 5 physical CPUs to allocate. Perfect explanation and rule of thumb. I will stick to the actual cores. Thank you! -T ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
[CentOS-virt] What are KVM guest cores?
Hi All, What are guest cores in KVM? Are they fake, like everything else in the guest? Just another process running on the host emulating a core? Or are the guest cores actually connected directly to the physical cores on my motherboard? Many thanks, -T ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] What are KVM guest cores?
Do you have a rule of thumb as to how many core to assign to a guest? For instance, with an Intel x5650 with 6 real and 12 hyperthreaded cores, how many cores would you assign to the guest? It fully depends on the load of your guests and how many guests you want/need to run on a single server. You need to perform some testing to know what will work the best in your case. One thing to remember though: In your case, if you create two guests with 12 virtual CPUs each, and one of them crashes and take all its 12 virtual CPUs up to 100%, it will essentially take most of the processing power away from the second guest, leaving the second guest in a close-to-useless state (depending on your scheduler, but you get the point). If you on the other hand had assigned 6 cores to each of them, the second guest would have remained unaffected, since it just uses the 6 cores with no load. So if your guest will not utilize the extra CPUs anyway, then don't assign them. Best regards Kenni ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
