Under Linux, the Page Cache accelerates many accesses to files on non volatile storage. This happens because, when it first reads from or writes to data media like hard drives, Linux also stores data in unused areas of memory, which acts as a cache.
Linux memory management tries to minimise disk access. To do this it will use any unused ram to cache, this is because reading from disk is slow compared to reading from memory. When an application needs memory the kernel should reduce the size of the cache and free up memory.
Like any other operating system, GNU/Linux has implemented a memory management efficiently and even more than that. But if any process is eating away your memory and you want to clear it, Linux provides a way to flush or clear ram cache.
Cached memory is memory that Linux uses for disk caching. However, this doesn't count as "used" memory, since it will be freed when applications require it. Hence you don't have to worry if a large amount is being used.
Using Free command to view Cache Usage
- # free -m.
- # dd if=/dev/random of=/root/data_file count=1400000. # for i in `seq 1 10`; do echo $i; cat data_file >> large_file; done.
- # cat large_file > /dev/null. # free -m.
- # echo 1 > /proc/sys/vm/drop_caches. # free -m.
ROM is an acronym for Read-Only Memory. It refers to computer memory chips containing permanent or semi-permanent data. Unlike RAM, ROM is non-volatile; even after you turn off your computer, the contents of ROM will remain. Almost every computer comes with a small amount of ROM containing the boot firmware.
Spooling overlaps the input and output of one job with the computation of another job. Buffering on other hand overlaps the input and output of one job with the computation of the same job. Spooling is more efficient than buffering.
Buffered memory is used in computers that have a lot of RAM such as servers and high-end workstations. Buffered memory should be avoided in gaming, business, and home computers because it slows the memory speed.
A buffer is a memory area that stores data being transferred between two devices or between a device and an application. Uses of I/O Buffering : Buffering is done to deal effectively with a speed mismatch between the producer and consumer of the data stream.
ADVANTAGES AND DISADVANTAGES OF BUFFER CACHE
- The use of buffers allows uniform disk access.
- The system places no data alignment restrictions on user processes doing I/O.
- Use of the buffer cache can reduce the amount of disk traffic, thereby increasing overall system throughput and decreasing response time.
A buffer is a solution that can resist pH change upon the addition of an acidic or basic components. It is able to neutralize small amounts of added acid or base, thus maintaining the pH of the solution relatively stable. This is important for processes and/or reactions which require specific and stable pH ranges.
In computer science, a data buffer (or just buffer) is a region of a physical memory storage used to temporarily store data while it is being moved from one place to another. However, a buffer may be used when moving data between processes within a computer.
1 : any of various devices or pieces of material for reducing shock or damage due to contact. 2 : a means or device used as a cushion against the shock of fluctuations in business or financial activity. 3 : something that serves as a protective barrier: such as. a : buffer state.