• 【收录】Linux下清理内存和Cache方法


    » 作者:LSX

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    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/lishixin/p/3036133.html
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