Shulou(Shulou.com)06/03 Report--

When linux reads and writes files, buffer cache is used to cache blocks on the physical disk, thus speeding up access to data on the disk. The contents of the buffer cache correspond to a block on disk, which is usually 1K and is contiguous. Under linux, in order to use physical memory more efficiently, the operating system automatically uses all free memory as Buffer Cache. When the program needs more memory, the operating system automatically reduces the size of the Cache. Under linux, you can view the memory usage of buffer cache with the commands cat / proc/meminfo and free-m.

#! / bin/bashif [`free-g | grep-w 'Mem:' | awk'{print$6}'`- ge 4]; then # buffer/cache > 4g start to clean up sync echo 1 > / proc/sys/vm/drop_caches echo 2 > / proc/sys/vm/drop_caches echo 3 > / procure sync echo [`free-g | grep-w 'Mem:' | awk' {print$6+$7}'`-ge 4] Then # centos 6 buffer+cache > 4G start cleaning sync echo 1 > / proc/sys/vm/drop_caches echo 2 > / proc/sys/vm/drop_caches echo 3 > / proc/sys/vm/drop_cachesfi

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