linux - NOHZ : local_softirq_pending 100

Question

今天，我找到了

kernel: NOHZ: local_softirq_pending 100

在 /var/log/messages 中。操作系统版本为CentOS-6.5(64bits)。

我通过谷歌搜索并找到了这个链接(https://kb.plesk.com/en/119599)。它说

These messages indicate that the system puts CPUs to sleep state instead of processing some software interrupt

但是我还是怀疑这样会不会对服务器造成伤害谁能给我一些建议？

Answer 1

您可能知道，CONFIG_NO_HZ_IDLE 选项启用无滴答空闲系统(又名“dynticks-idle 系统”)。

根据https://www.kernel.org/doc/Documentation/timers/NO_HZ.txt

There are situations in which idle CPUs cannot be permitted to enter either dyntick-idle mode or adaptive-tick mode, the most common being when that CPU has RCU callbacks pending.

The CONFIG_RCU_FAST_NO_HZ=y Kconfig option may be used to cause such CPUs to enter dyntick-idle mode or adaptive-tick mode anyway. In this case, a timer will awaken these CPUs every four jiffies in order to ensure that the RCU callbacks are processed in a timely fashion.

Another approach is to offload RCU callback processing to "rcuo" kthreads using the CONFIG_RCU_NOCB_CPU=y Kconfig option. The specific CPUs to offload may be selected via several methods…"

因此，一个解决方案可能只是使用 CONFIG_RCU_FAST_NO_HZ=y 重建内核和/或通过内核参数 nohz=off 禁用动态时钟(“永远不要忽略调度时钟时钟”，这可能会产生其他副作用)。