Linux cgroups：以绝对值限制CPU使用率,不依赖于CPU速度
作者：互联网
我有一台2.4GHz处理器的服务器.并且有几个cgroup,每个允许使用25％的CPU.这相当于600MHz.
然后我用更快的CPU更换CPU,比方说3.0GHz.如果我使用cpu.shares,我的容器将继续获得3.0GHz的25％,现在等于750MHz.
这意味着在更换CPU之后,我必须重新配置我的cgroup,使它们消耗的CPU不超过20％.
有没有办法在CPU升级期间避免这种麻烦？
解决方法:
股票是相对的.例如,分配25％的CPU意味着cgroup将“至少”观察到大部分CPU,但它可以使用更多.从red hat docs on cgroups：
Note that shares of CPU time are distributed per all CPU cores on multi-core systems. Even if a cgroup is limited to less than 100% of CPU on a multi-core system, it may use 100% of each individual CPU core.
…
The actual amount of CPU time that is available to a cgroup can vary depending on the number of cgroups that exist on the system. If a cgroup has a relative share of 1000 and two other cgroups have a relative share of 500, the first cgroup receives 50% of all CPU time in cases when processes in all cgroups attempt to use 100% of the CPU. However, if another cgroup is added with a relative share of 1000, the first cgroup is only allowed 33% of the CPU (the rest of the cgroups receive 16.5%, 16.5%, and 33% of CPU).
如果要对CPU带宽进行硬限制,可以使用cpu.cfs_quota_us和cpu.cfs_period_us.从Kernel’s CFS docs开始：
The bandwidth allowed for a group is specified using a quota and period. Within each given “period” (microseconds), a group is allowed to consume only up to “quota” microseconds of CPU time. When the CPU bandwidth consumption of a
group exceeds this limit (for that period), the tasks belonging to its hierarchy will be throttled and are not allowed to run again until the next
period.
但是,这两个选项都不允许您在不同CPU之间移植组,而无需更改cgroups配置.
标签：linux,cpu,limit,cgroups,quota 来源： https://codeday.me/bug/20190812/1642209.html