Linux内存参数swappiness
与cgroup关系
swappiness是cgroup v1的特性，在cgroup v2已经被替代。
swapiness is a cgroupvs1 feature, and it has no counterpart on cgroupsv2. (the new latency stuff is maybe a better replacement though).
swappiness实现很糟糕，systemd不打算再维护它了。
swappiness作用范围
Similar to /proc/sys/vm/swappiness, but affecting a hierarchy of groups only.
Following cgroups' swappiness can't be changed. - root cgroup (uses /proc/sys/vm/swappiness). - a cgroup which uses hierarchy and it has other cgroup(s) below it. - a cgroup which uses hierarchy and not the root of hierarchy.
关于swappiness=0
Note that a value of 0 does not prevent process memory being swapped out; swap out might still happen when there is a shortage of system memory because the global virtual memory management logic does not read the cgroup value. To lock pages completely, use mlock() instead of cgroups.
swappiness设置为0就相当于关闭swap么？
不是的，关闭swap要使用swapoff命令。swappiness只是在内存发生回收操作的时候用来平衡cache回收和swap交换的一个参数，调整为0意味着，尽量通过清缓存来回收内存。
参考
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