Memory ballooning in OS


Some operating systems use memory ballooning to optimize memory usage in virtualized environments. It entails dynamically reallocating memory resources among virtual machines (VMs) based on their current requirements. In this article, we will explore what is Memory Ballooning, and its advantages and disadvantages in detail.

Memory Ballooning

Memory ballooning is a technique used in virtualized environments to optimize the use of memory resources. It allows the operating system to reclaim unused memory from one virtual machine and allocate it to another that requires it. This helps to prevent resource waste and improves overall performance. Memory ballooning is achieved through a "balloon driver" that can request memory from the host operating system and release it when it is no longer needed. When a virtual machine needs more memory, its balloon driver requests it from the host. When it has unused memory, the balloon driver returns it to the host.

Working of the Balloon Driver in Memory Ballooning

The balloon driver used for memory ballooning typically operates as follows −

  • The balloon driver runs in the background of each VM.

  • When the host operating system requires memory, it sends a request to the balloon driver of each VM to release some memory.

  • The balloon driver then inflates a balloon within the VM, fooling the guest operating system into thinking it has less memory than it actually does. The guest operating system begins swapping out unused memory pages to disc.

  • The reclaimed memory is returned to the host operating system by the balloon driver.

  • When the VM requires additional memory, the balloon driver requests it from the host operating system. The host then deflates the balloon and allocates memory to the VM.

The host operating system or a virtualization layer, such as a hypervisor, can implement memory ballooning. To further optimize memory usage in virtualized environments, it is typically used in conjunction with other memory optimization techniques such as memory overcommitment and memory compression.

While memory ballooning has several benefits for optimizing memory usage in virtualized environments, it is critical to carefully consider the potential drawbacks and implement appropriate mitigation measures. This can include monitoring the performance impact of memory ballooning, implementing appropriate security measures, and combining memory ballooning with other memory optimization techniques.

Advantages of Memory Ballooning in virtualized environments

Memory ballooning has several advantages in virtualized environments −

Efficient use of memory resources

Memory ballooning allows unused memory to be reclaimed and allocated to virtual machines (VMs) that require it. This helps to optimize memory usage and reduces resource waste.

Improved performance

Memory ballooning can help to prevent performance degradation or crashes caused by VMs running out of memory by ensuring that each VM has enough memory.

Dynamic allocation

Memory ballooning allows for the dynamic allocation of memory resources based on the changing needs of virtual machines. As a result, memory can be allocated where it is most needed, improving overall system performance.

Cost savings

Memory ballooning can help to reduce the need for additional physical memory and improve the overall cost-effectiveness of virtualized environments by optimizing memory usage.


Most modern operating systems and hypervisors support memory ballooning, making it a widely compatible technique for optimizing memory usage in virtualized environments.

Memory ballooning is a useful technique for improving the efficiency and performance of virtualized environments, as well as lowering costs and improving compatibility.

Disadvantages of Memory Ballooning in virtualized environments

Although memory ballooning has several benefits for optimizing memory usage in virtualized environments, there are some drawbacks to consider

Performance impact

Memory ballooning adds overhead to the host operating system, which can have an impact on overall system performance. In some cases, this can lead to decreased VM performance.


Memory ballooning necessitates the use of additional software components and configurations, which can increase the complexity of virtualized environments. This can make managing and troubleshooting issues more difficult.

Compatibility issues

While modern operating systems and hypervisors widely support memory ballooning, there may be compatibility issues with older systems or less common virtualization platforms.

Security risks

Attackers may target the balloon driver used for memory ballooning in order to gain unauthorized access or execute malicious code. Although this risk can be reduced by implementing appropriate security measures, it remains a potential concern.

Inefficient memory usage

Memory ballooning is a technique that helps optimize memory usage in virtual machines, but it may not always work well when there are many virtual machines with different memory needs. In these cases, memory may not be used efficiently.


Memory ballooning can help computer systems use memory more efficiently in virtualized environments. However, it's important to weigh the benefits and drawbacks and take steps to prevent any negative effects. By effectively managing virtual environments, organizations can enhance performance and save costs.

Updated on: 04-May-2023


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