Linux memory available is the amount of physical memory (RAM) that is not being used by the operating system or applications. This can be due to the operating system not requiring as much memory as is physically available, or because applications are not using all of the memory that is available to them.
Linux Memory Management
Linux Memory Management
Linux is a multitasking operating system, meaning that it can run multiple programs at the same time. To do this, it needs to be able to quickly and efficiently switch between the different programs that are running. Part of how it does this is by using memory management.
Linux uses a process called paging to manage memory. Paging is a technique where each process is given its own section of memory, called a page. When a process needs to access memory, the operating system checks to see if the memory is in the process’s page. If it is, the operating system allows the process to access it. If the memory is not in the process’s page, the operating system retrieves it from disk and then allows the process to access it.
Paging helps improve performance by allowing the operating system to quickly find the memory that a process needs. It also helps improve security by keeping processes from being able to access memory that they should not have access to.
Linux Memory Allocation
Linux Memory Allocation
Linux is a multitasking operating system, which means that it can run multiple programs at the same time. To do this, it needs to have a way to keep track of all the different programs that are running, and it does this by using memory.
When a program is started, Linux will allocate a certain amount of memory to it. This memory is used to store the program’s code and data. The amount of memory that a program needs will depend on the size of the program and the amount of data that it needs to store.
If a program tries to use more memory than it has been allocated, Linux will try to allocate more memory to it. If there is not enough memory available, Linux will start to swap some of the data from memory to disk. This can slow down the program, and if there is a lot of swapping, the program can become unresponsive.
Linux Memory Usage
Linux Memory Usage
Linux is a UNIX-like operating system that was designed to provide users with a free and open source alternative to proprietary UNIX systems. Linux is typically packaged in a software distribution, which includes the Linux kernel, supporting utilities and libraries, and a graphical user interface (GUI).
As with any operating system, Linux uses memory to store data and programs while they are running. The amount of memory used by Linux will vary depending on the distribution and applications being used. However, Linux is generally very efficient with memory usage and can run on systems with as little as 128MB of RAM.
To check your system’s memory usage in Linux, you can use the command line tool ‘free’. This will show you information on the total amount of memory, the amount of used memory, and the amount of free memory. You can also use the ‘top’ command to see real-time information on Linux memory usage.
Linux Memory Types
There are three types of Linux memory: physical memory, virtual memory, and swap space.
Physical memory is the actual RAM in your computer. Virtual memory is a portion of your hard drive that is used as if it were RAM. Swap space is a portion of your hard drive that is used as an overflow for physical memory or virtual memory.
When your computer starts to run low on physical memory, it will start to use virtual memory. If there is not enough virtual memory available, the computer will start to use swap space.
Linux Memory Model
The Linux Memory Model defines how a multi-threaded program will work under the Linux kernel. It is important to understand the memory model because it defines the rules for how data is shared between threads, and how data is accessed by the kernel.
The Linux Memory Model is based on the idea of a shared virtual memory space. This means that all threads have access to the same address space, and can read and write to any location in memory. However, each thread has its own private data that is not visible to other threads.
The Linux Memory Model defines two types of data: shared data and private data. Shared data is data that is visible to all threads, and can be read or written by any thread. Private data is data that is only visible to the thread that owns it, and can only be read or written by that thread.
The Linux Memory Model also defines how data is synchronized between threads. When a thread reads or writes to a location in memory, it first checks to see if the location is in its own private data. If it is, then the thread can read or write to the location without synchronizing with other threads. However, if the location is in shared data, then the thread must acquire a lock before it can read or write to the location. This lock is released when the thread is finished reading or writing to the location.
Linux Memory Management Implementation
Linux Memory Management Implementation
Linux memory management is a complex topic, but in general, the kernel tries to make use of as much physical memory as possible while keeping the system stable. This is done by using a combination of techniques such as demand paging, page caching, and swap space.
Demand paging is a technique where pages are only loaded into memory when they are needed. This is different from traditional paging systems where all pages are always loaded into memory. With demand paging, the kernel can free up memory when it is not being used.
Page caching is a technique where frequently used pages are kept in memory so that they can be quickly accessed. This helps to improve performance since the pages don’t need to be read from disk every time they are accessed.
Swap space is a reserved area on disk that can be used to store pages that are not being used. This allows the kernel to free up memory when necessary. When a page is needed again, it can be read back from the swap space.
Linux Memory Management Internals
Linux memory management is a complex topic, but in general, the Linux kernel tries to use as much physical memory as possible for caching purposes. This helps improve performance by reducing the number of times the CPU has to access the slow main memory. When a program needs more memory than is available in the cache, the kernel will start swapping out pages of memory to disk. This can cause a significant slowdown, so it is important to have enough physical memory (RAM) in your system to avoid this.