Re: How much physical memory can be used to run domains in a KVM machine?
On Friday 17 July 2009 17:56:49 sudhir kumar wrote: On Fri, Jul 17, 2009 at 12:47 PM, Dor Laordl...@redhat.com wrote: On 07/17/2009 08:50 AM, Zhang Qian wrote: Hi, I have a KVM box which has 4GB physical memory totally, I'd like to know how much I can use to run my domains, and how much will be reserved by hypervisor(KVM) itself? Thanks! KVM and the Linux host use relatively low amount of memory. Unlike other hypervisors you know, kvm does not reserve memory and also is able to swap the guest memory, so you can even use more than 4G for your Is that true? I think we can not allocate memory more than the physical RAM. Or does upstream kvm supports it? My kvm version is not that old but memory allocation failed for me when I tried to give the whole memory on my host to the guest. It's not specific to KVM. QEmu use malloc()/mmap() to allocate memory for KVM, which is controlled by Linux kernel memory overcommit policy. Linux kernel didn't support memory overcommit by default. You can refer to Document/vm/overcommit-accounting and other related document to enable it. -- regards Yang, Sheng guest. (Just note swapping will be slow) Regards, Qian -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: How much physical memory can be used to run domains in a KVM machine?
On 07/17/2009 08:50 AM, Zhang Qian wrote: Hi, I have a KVM box which has 4GB physical memory totally, I'd like to know how much I can use to run my domains, and how much will be reserved by hypervisor(KVM) itself? Thanks! KVM and the Linux host use relatively low amount of memory. Unlike other hypervisors you know, kvm does not reserve memory and also is able to swap the guest memory, so you can even use more than 4G for your guest. (Just note swapping will be slow) Regards, Qian -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: How much physical memory can be used to run domains in a KVM machine?
On Fri, Jul 17, 2009 at 12:47 PM, Dor Laordl...@redhat.com wrote: On 07/17/2009 08:50 AM, Zhang Qian wrote: Hi, I have a KVM box which has 4GB physical memory totally, I'd like to know how much I can use to run my domains, and how much will be reserved by hypervisor(KVM) itself? Thanks! KVM and the Linux host use relatively low amount of memory. Unlike other hypervisors you know, kvm does not reserve memory and also is able to swap the guest memory, so you can even use more than 4G for your Is that true? I think we can not allocate memory more than the physical RAM. Or does upstream kvm supports it? My kvm version is not that old but memory allocation failed for me when I tried to give the whole memory on my host to the guest. guest. (Just note swapping will be slow) Regards, Qian -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html -- Sudhir Kumar -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: How much physical memory can be used to run domains in a KVM machine?
On (Fri) Jul 17 2009 [15:26:49], sudhir kumar wrote: On Fri, Jul 17, 2009 at 12:47 PM, Dor Laordl...@redhat.com wrote: On 07/17/2009 08:50 AM, Zhang Qian wrote: Hi, I have a KVM box which has 4GB physical memory totally, I'd like to know how much I can use to run my domains, and how much will be reserved by hypervisor(KVM) itself? Thanks! KVM and the Linux host use relatively low amount of memory. Unlike other hypervisors you know, kvm does not reserve memory and also is able to swap the guest memory, so you can even use more than 4G for your Is that true? I think we can not allocate memory more than the physical RAM. Or does upstream kvm supports it? My kvm version is not that old but memory allocation failed for me when I tried to give the whole memory on my host to the guest. What was the error? Also kvm only allocates memory for the guest when the guest needs it so even if you give all your host memory to the guest, it doesn't mean the guest will start using it immediately. Amit -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
How much physical memory can be used to run domains in a KVM machine?
Hi, I have a KVM box which has 4GB physical memory totally, I'd like to know how much I can use to run my domains, and how much will be reserved by hypervisor(KVM) itself? Thanks! Regards, Qian -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
