The balloon driver contacts the hypervisor with the details of the memory it has been allocated. The hypervisor removes the ballooned memory from the VM, lowering memory consumed by that VM. Memory compression and swapping can cause serious performance problems for VM performance. TPS and ballooning are relatively slow compared to swapping, if you need memory fast, swapping may be used. Try Longitude Live Online Demo! Please log in using the credentials below: Username: demo Password: longitude.
Start Demo. Download the whitepaper. Leave a Reply Cancel reply Your email address will not be published. Sign In. Forgot Password? Remember Me. Memory Reclamation Techniques. TPS does not affect VM performance. Best Practices for Capacity Planning for Memory. Do not use more memory than is needed for your VM. Ideally, consumed memory for the VM should be close to the memory used by the guest OS, plus overhead for running the VM.
This allocation works under the assumption that the virtual machines will not use all of their memory at the same time. To explicitly tell the virtual machine instance that it has more memory available than was requested from the cluster, edit the virtual machine configuration file and set spec. This process is called memory overcommitment. In this example, M is requested from the cluster, but the virtual machine instance is told that it has M available.
As long as there is enough free memory available on the node, the virtual machine instance will consume up to M. The same eviction rules as those for pods apply to the virtual machine instance if the node is under memory pressure. A small amount of memory is requested by each virtual machine instance in addition to the amount that you request. This additional memory is used for the infrastructure that wraps each VirtualMachineInstance process.
Traditional hypervisors scan all guest memory and compute checksums, also called hashes, for every single memory page. Then, they look for pages with identical hashes and compare the entire content of those pages. If two pages produce the same hash, it is very likely that the pages are identical in content. This process can take rather long, especially if the system is not idling. As a result, the additional memory only becomes available after a significant amount of time, such as hours or sometimes days.
It can therefore achieve most of the possible savings of page sharing almost immediately and with almost no overhead. Page Fusion is also much less likely to be confused by identical memory that it will eliminate, just to learn seconds later that the memory will now change and having to perform a highly expensive and often service-disrupting reallocation.
To enable Page Fusion for a VM, use the following command:. You can observe Page Fusion operation using some metrics. Enabling Page Fusion might indirectly increase the chances for malicious guests to successfully attack other VMs running on the same host. See Potentially Insecure Operations. All rights reserved. Legal Notices. JavaScript is disabled on your browser. Please enable JavaScript to enjoy all the features of this site.
Memory Overcommitment. Memory Ballooning. Page Fusion. Previous Guest Control of Applications.
0コメント