Memory Ballooning in OS

Memory ballooning is a feature of most virtualization platforms to make more efficient use of physical memory for virtual servers. Memory ballooning is a critical component of modern virtualized data storage architectures. With both physical and virtual assets requiring memory resources, a variety of methods for claiming, releasing, and reclaiming memory are required.

In this article, we are going to discuss memory ballooning, what is hypervisor what re different processes of memory ballooning are, its issues and importance, advantages and disadvantages of memory ballooning in operating systems. Here below is a detailed discussion of Memory Ballooning.

What is Memory Ballooning?

Memory ballooning is a common virtualization technology technique that makes use of virtual machine memory. Memory ballooning is a memory management feature found in most virtualization platforms that allows a host system to artificially expand its memory pool by utilizing or reclaiming unused memory previously allocated to various virtual machines.
This is accomplished by installing a balloon driver on the guest operating system, with which the hypervisor communicates when it needs to reclaim memory via ballooning.
You can think of it as “stretching” regular physical memory to a greater extent. This enables a server with 32 GB of memory to host up to 64 GB of virtual machines (actual mileage will vary based on the workloads).

What is a Hypervisor?

Memory ballooning occurs within the context of a virtualization hypervisor. A hypervisor is a technology that allows virtual machines to run by providing a virtual abstraction layer for software.
Today, several hypervisor technologies are widely used, including VMware ESXi, Microsoft Hyper-V, and the open source Xen and KVM technologies. Each hypervisor can be used to enable guest virtual machines, which run operating systems and applications in a virtualized fashion.
Drivers are used by the hypervisor across running guest virtual machines to handle various requirements, such as resource constraints such as virtual CPUs, disc space, and memory. The balloon drivers operate across virtual machines, allowing a hypervisor to reallocate memory from one virtual machine to another.

Process of Memory Ballooning

Understanding how a hypervisor works is inextricably linked to understanding the memory ballooning process. A hypervisor abstracts finite system resources and then allocates them to virtual machine processes that are running.

• Host Physical Memory: The underlying server or cloud platform has a set amount of installed system memory, which represents the absolute total amount of available memory.
• Guest Physical Memory: In order to provide resources to running virtual machines, the hypervisor is given a portion of the host’s physical memory. The maximum amount of memory available to the hypervisor is referred to as the guest physical memory.
• Guest Virtual Memory: The hypervisor allocates a portion of its total memory resources to the running guest virtual machines as virtual memory.

In the memory ballooning model, one virtual machine that, for example, had 8 GB of guest virtual memory allocated to it but was not using it could have some of that RAM reallocated to another running virtual machine that needed the extra memory.

The balloon driver keeps track of memory allocations as they move from one virtual machine to the next. The primary goal of memory ballooning is to provide a virtual machine with the memory it requires to meet a spike in process or application demand. This occurs even if it does not normally have sufficient memory allocated to it.

Working of Memory Ballooning

Below are the mentioned steps in the working of Memory ballooning.

Step 1 – Balloon Driver Installation: The memory ballooning system begins with the set up of a balloon motive force within each visitor operating device going for walks within the VMs. This balloon motive force is normally provided by the hypervisor or virtualization platform.

Step 2 – Memory Pressure Detection: The hypervisor monitors the memory utilization of the host gadget and identifies conditions in which there may be memory strain, consisting of whilst the bodily memory is nearly completely applied or while competition for memory assets is detected.

Step 3 – Ballooning Activation: When memory stress is detected, the hypervisor instructs the balloon drivers hooked up in the visitor VMs to activate. Each balloon driver inflates, successfully claiming memory from inside the visitor OS.

Step 4 – Memory Reclamation: By inflating, the balloon driver within every VM consumes a portion of the visitor’s memory, making it unavailable for use by means of applications within that VM. This reclaimed reminiscence is then made available for allocation to different VMs or for other device procedures at the host.

Step 5 – Dynamic Adjustment: The quantity of reminiscence allocated to the balloons inside the VMs can be dynamically adjusted through the hypervisor based on changing call for and aid availability. This guarantees efficient utilization of bodily reminiscence sources across all VMs.

Step 6 – Balloon Deflation: When memory pressure decreases and further physical memory will become to be had at the host gadget, the hypervisor can teach the balloon drivers to deflate. This releases the previously claimed memory lower back to the guest OS, making it available to be used by packages within the VM

Features of Memory Ballooning

• Dynamic Memory Management: Memory ballooning enables dynamic adjustment of reminiscence allocation among virtual machines (VMs) based on real-time demand and gadget conditions. It allows for bendy and green usage of bodily memory resources in virtualized environments.
• Resource Optimization: By reclaiming memory from underutilized VMs and reallocating it to VMs with better demand, memory ballooning optimizes standard memory utilization across the virtualized infrastructure. This enables save you reminiscence overcommitment and reduces the hazard of performance degradation because of reminiscence rivalry.
• Adaptive Balloon Sizing: Memory ballooning supports adaptive sizing of balloon drivers within guest VMs, permitting them to inflate or deflate dynamically in reaction to changing workload styles and reminiscence pressure. This adaptive conduct guarantees that reminiscence resources are allotted correctly with out compromising overall performance or balance.
• Integration with Hypervisor: Memory ballooning is tightly included with the hypervisor or virtualization platform, permitting centralized manipulate and control of reminiscence allocation regulations and settings. Administrators can configure and screen reminiscence ballooning conduct through the hypervisor control interface or command-line equipment.
• Guest OS Support: Memory ballooning requires help from the guest running structures strolling inside VMs. Balloon drivers are usually set up inside the guest OS to facilitate communique with the hypervisor and enable memory reclamation. Support for balloon drivers may additionally range depending at the virtualization platform and guest OS compatibility.
• Performance Monitoring: Hypervisors offer integrated monitoring equipment and overall performance metrics for monitoring memory utilization, balloon inflation/deflation costs.

Issues with Memory Ballooning

• High Balloon Memory Utilization: High utilization is one of the potential problems that can arise. It is possible that the balloon driver will consume so much memory that the hypervisor will not have enough resources to operate at peak performance.
• Performance: If multiple virtual machines request balloon memory at the same time, there may be a spike in CPU and physical disc usage as the hypervisor pulls resources via memory swapping techniques, degrading overall system performance even further.

Importance of Memory Ballooning

• Resource optimization: Memory ballooning takes memory from virtual machines that aren’t currently using all available memory, and then reallocates the unused memory to a virtual machine that needs the extra resources.
• Memory availability: Memory ballooning, as opposed to simply not providing a virtual machine with the resources it requires due to a spike in demand or process, provides more memory when needed.
• Lower cost: Memory efficiency reduces the need to deploy more physical servers or allocate more physical memory, which incurs additional operational and energy costs. 

Advantages of Memory Ballooning

• The ballooning will prevent the system from deteriorating even if the workload on the connection increases.
• Using the maximum amount of memory in the connection is the main benefit of putting this system into place.
• Because it is dynamic, this technique may be adjusted to meet the needs of the business or the industry.

Disadvantages of Memory Ballooning

• When a balloon uses a lot of memory and the hypervisor runs out of memory to allocate to the incoming balloons that require memory, this is known as overutilization of resources.
• System performance may be impacted if multiple virtual machines in an idle state seek memory since the hypervisor operates on the memory swapping and sharing principle. Thus, the mutual exclusion principle ought to be applied.

Frequently Asked Question on Memory Ballooning – FAQs

How do you check memory ballooning?

Memory Balloning is shown on a host in the Memory (Balloon) chart. The host Performance tab’s Home view is where you may find this chart. Total amount of guest physical memory recovered by the balloon driver for each of the host’s powered-on virtual machines

What is the purpose of memory ballooning?

A hypervisor can employ a technique called memory ballooning to recover unused memory from certain guest virtual machines (VMs) and share it with other virtual machines running on the real host system.

Is memory ballooning supported by all virtualization platforms?

Do all hypervisors support memory ballooning? Memory ballooning is supported by the majority of widely used hypervisors, including VMware ESXi, Microsoft Hyper-V, and KVM. But features and implementation could differ throughout platforms.