Modern offices are crowded with personal computers. While studies have shown these to be idle most of the time, they remain powered, consuming up to 60% of their peak power. Hardware based solutions engendered by PC vendors (e.g., low power states, Wake-on-LAN) have proven unsuccessful because, in spite of user inactivity, these machines often need to remain network active in support of background applications that maintain network presence.
Recent solutions have been proposed that perform consolidation of idle desktop virtual machines. However, desktop VMs are often large requiring gigabytes of memory. Consolidating such VMs, creates large network transfers lasting in the order of minutes, and utilizes server memory inefficiently. When multiple VMs migrate simultaneously, each VM’s experienced migration latency grows, and this limits the use of VM consolidation to environments in which only a few daily migrations are expected per VM. This thesis introduces partial VM migration, an approach that transparently migrates only the working set of an idle VM, by migrating memory pages on-demand. It creates a partial replica of the desktop VM on the consolidation server by copying only VM metadata, and transferring pages to the server, as the VM accesses them. This approach places desktop PCs in low power state when inactive and resumes them to running state when pages are needed by the VM running on the consolidation server.
Jettison, our software prototype of partial VM migration for off-the-shelf PCs, can
deliver 78% to 91% energy savings during idle periods lasting more than an hour, while providing low migration latencies of about 4 seconds, and migrating minimal state that is under an order of magnitude of the VM’s memory footprint. In shorter idle periods of up to thirty minutes, Jettison delivers savings of 7% to 31%.
We present two approaches that increase energy savings attained with partial VM migration, especially in short idle periods. The first, Context-Aware Selective Resume, expedites PC resume and suspend cycle times by supplying a context identifier at desktop resume, and initializing only devices and code that are relevant to the context. CAESAR, the Context-Aware Selective Resume framework, enables applications to register context vectors that are invoked when the desktop is resumed with matching context. CAESAR increases energy savings in short periods of five minutes to an hour by up to 66%.
The second approach, the low power page cache, embeds network accessible low power hardware in the PC, to enable serving of pages to the consolidation server, while the PC is in low power state. We show that Oasis, our prototype page cache, addresses the shortcomings of energy-oriented on-demand page migration by increasing energy savings, especially during short idle periods. In periods of up to an hour, Oasis increases savings by up to twenty times.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/35778 |
| Date | 02 August 2013 |
| Creators | Bila, Nilton |
| Contributors | de Lara, Eyal |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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