## 1 Introduction  
Deployed in the recent decade, Ethernet speeds have been increased from 10 Gbps to 40 Gbps and 100 Gbps and will go in the future towards Terabit per second, as stated in the Ethernet Alliance roadmap [1]. However, implementation and deployment of multi-gigabit applications, optimization of their performance and accuracy of the transmission speed remain significant challenges [2]. As a representative network application for which the accuracy of timing functions is the performance basis, we put forward the following requirements: the application shall have strict timing requirements, the application must be based on high-speed data transmission, and the application must also have practical applicability in modern networks. In this case, the precision of available bandwidth estimation applications is strictly tied to the precision of timing operations and meets mentioned requirements. Recent network measurement projects, focusing on performance evaluation, capture such performance metrics as path capacity (maximum possible throughput) and available bandwidth(maximum available throughput) of a network path. Estimation of these parameters requires creating explicit probe packets that consume CPU resource and possess enough timers precision to generate accurate timestamps of probe packets under bursty traffic conditions. Moreover, in this kind of application, it takes more than 200 time acquisition function calls per packet and about one sleep operation per issued data packet. Because of virtualization, datacenter tenants no longer have direct access to the underlying physical network. The extra layer of indirection makes it hard to optimize application performance. AvB can measure the underlying network and provide performance metrics to the virtualized applications to optimize tasks such as VM placement and route selection [2]. Therefore, the general requirements of such time-sensitive networking applications are based on precise and rapid timing measurements, such as low latency, dealing with a limited performance of the end systems (e.g., frequency of the kernel interrupts), adoption of inter-packet interval, etc. In this paper, we address this challenge and aim to evaluate how the accuracy of modern timers can influence the result measurements of network performance under the virtualization conditions. For this, we have extended our previous research in timing operations with its performance influence on the real network application. As a matter of fact, keeping high time precision of control algorithms and meeting soft real-time requirements is a complex problem on modern multi-purpose operating systems such as Linux. This task is becoming even more challenging under virtual environments which require efficient access to the physical platform through the software middleware of the hypervisor or host operating system [3; 4; 5]. Thus, timing operations used by the applications are usually dependent on certain software layers in the operating system. As our previous research has shown [6; 7], even operating systems running on bare hardware are often not efficient enough for high-performance applications. Running such operations in virtual environments potentially adds a significant overhead to these operations by the hypervisor OS, by means of passing data to bare hardware by it as well as by the means of the guest OS. However, the use of virtual machines as an intermediate layer for simplification of deployment and operations of high-performance applications is \"tempting\". Virtualization is very widely used in data centers and in cloud environments. The possibility to run high-performance applications from out of a virtual environment is a very important factor for deployments of such applications, in which timer performance plays a significant role. In the present work, we consider the question of whether it is feasible and if so, on which systems and at which \"costs\".