VMware has released a paper titled:”Deploying Extremely Latency-Sensitive Applications in VMware vSphere 5.5“. The Paper which contains 17 pages provides details about a new per-VM feature introduced in vSphere 5.5. called Latency Sensitivity.
Latency Sensitivity allows virtual machines to exclusively own physical cores, thus avoiding overhead related to CPU scheduling and contention. Combined with a pass-through functionality, which bypasses the network virtualization layer, applications can achieve near-native performance in both response time and jitter.
The paper presents the following topcis:
• It explains major sources of latency increase due to virtualization, which are divided into two categories:
- Contention created by sharingresourcesand
- overhead due to the extra layers of processing for virtualization.
• It presents details of the latency-sensitivity feature that improves performance in terms of both response time and jitter by eliminating the major sources of extra latency added by using virtualization.
• It presents evaluation results demonstrating that the latency-sensitivity feature combined with pass-through mechanisms considerably reduces both median response time and jitter compared to the default configuration, achieving near-native performance.
• It discusses the side effects of using the latency-sensitivity feature and presents best practices
Evaluation results show that the latency-sensitivity feature combined with pass-through mechanisms such as SR-IOV helps to achieve a near-native performancein terms of both response time and jitter. For example, ping(median) response time reduces from 34us to 20us, showing only 2us difference from a native setup (18us).Further, when used with a specialized NIC, 90th percentile response time of 6us is achieved with a NetperfTCP_RR workload, showing the same performance compared to a native setup.