Linux下清理記憶體和Cache方法

Linux下清理記憶體和Cache方法 頻繁的檔案訪問會導致系統的Cache使用量大增 $ free –m total used free shared buffers cached Mem: 3955 3926 28 0 55 3459 -/+ buffers/cache: 411 3544 Swap: 5726 0 5726 free記憶體減少到幾十兆，系統運行緩慢 運行sync將dirty的內容寫回硬碟 $sync 通過修改proc系統的drop_caches清理free的cache $echo 3 > /proc/sys/vm/drop_caches drop_caches的詳細文檔如下： Writing to this will cause the kernel to drop clean caches, dentries and inodes from memory, causing that memory to become free. 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: * echo 3 > /proc/sys/vm/drop_caches As this is a non-destructive operation, and dirty objects are notfreeable, the user should run “sync” first in order to make sure allcached objects are freed. This tunable was added in 2.6.16. 修改/etc/sysctl.conf 添加如下選項後就不會記憶體持續增加 vm.dirty_ratio = 1 vm.dirty_background_ratio=1 vm.dirty_writeback_centisecs=2 vm.dirty_expire_centisecs=3 vm.drop_caches=3 vm.swappiness =100 vm.vfs_cache_pressure=163 vm.overcommit_memory=2 vm.lowmem_reserve_ratio=32 32 8 kern.maxvnodes=3 上面的設定比較粗暴，使cache的作用基本無法發揮。需要根據機器的狀況進行適當的調節尋找最佳的折衷 來源 http://blog.lishixin.net/linux/1222.html