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  • Linux下清理内存和Cache方法

    暂时目前的环境处理方法比较简单:

    在root用户下添加计划任务:

    */10 * * * * sync;echo 3 > /proc/sys/vm/drop_caches;     

    每十分钟执行一次,先将脏数据写回硬盘,之后释放缓存页和入口信息和节点信息等;

    -------------------参考链接:https://www.linuxidc.com/Linux/2010-03/24939.htm

    Linux下清理内存和Cache方法 /proc/sys/vm/drop_caches


    Linux下清理内存和Cache方法 /proc/sys/vm/drop_caches
     

    频繁的文件访问会导致系统的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内存减少到几十兆,系统运行缓慢

    运行sync将dirty的内容写回硬盘
    $sync

    通过修改proc系统的drop_caches清理free的cache
    $echo 3 > /proc/sys/vm/drop_caches

    drop_caches的详细文档如下:
    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 添加如下选项后就不会内存持续增加
    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

    上面的设置比较粗暴,使cache的作用基本无法发挥。需要根据机器的状况进行适当的调节寻找最佳的折衷。

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  • 原文地址:https://www.cnblogs.com/the-tops/p/8798605.html
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