Free command details and releases linuxCache

Article Title: Free command details and release of linuxCache. Linux is a technology channel of the IT lab in China. Including desktop applications, Linux system management, kernel research, embedded systems, open source, and other basic categories. Because of the LINUX kernel mechanism, you generally do not need to release the used cache. The cached content can increase the file and read/write speed. First let's talk about the free command to see the memory [root @ yuyii proc] # free total used free shared buffers cached Mem: 515588 295452 220136 2060 0 64040 229352-/+ buffers/cache: 286236 Swap: 682720 112 682608 the first line describes the memory usage of the system from a global perspective: total -- total physical memory used -- used memory. Generally, this value is relatively large, this value includes the cache + memory used by the application free -- completely unused memory shared -- Application shared memory buffers -- cache, which is mainly used for directory, inode value (this value can be seen in the ls directory) cached -- cache, used for the opened file note: total = used + free used = buffers + cached (mayb E add shared also) the second line describes the memory usage of the application: the first value indicates-buffers/cache-the memory size used by the application, used minus the cache value + buffers/cache -- memory size used by all available applications, free plus cache Value note: -buffers/cache = used-buffers-cached + buffers/cache = free + buffers + cached the third line indicates the use of swap: used -- used free -- unused cache for release: to free pagecache: echo 1>/proc/sys/vm/drop_caches To free dentries and inodes: echo 2>/proc/sys/vm/drop_caches To free pagecache, dentries and inodes: ec Ho 3>/proc/sys/vm/drop_caches indicates that it is best to sync before release to prevent data loss.