内核线程和用户态进程的cpu利用率过高时的调试方法

最新推荐文章于 2025-07-07 17:25:24 发布

smartzzm

最新推荐文章于 2025-07-07 17:25:24 发布

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本文介绍Linux中kworker进程导致CPU占用高的原因及解决方法。通过创建CPU回溯找出频繁调用的代码路径，定位到具体问题所在，并提供实例说明如何通过卸载有问题的模块来降低CPU负载。

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--kworker

What is kworker? kworker means a Linux kernel process doing "work" (processing system calls). You can have several of them in your process list: kworker/0:1 is the one on your first CPU core, kworker/1:1 the one on your second etc..

Why does kworker hog your CPU? To find out why a kworker is wasting your CPU, you can create CPU backtraces: watch your processor load (with top or something) and in moments of high load through kworker, execute echo l > /proc/sysrq-trigger to create a backtrace. (On Ubuntu, this needs you to login with sudo -s). Do this several times, then watch the backtraces at the end of dmesg output. See what happens frequently in the CPU backtraces, it hopefully points you to the source of your problem.

Example: e1000e. In my case, I found a backtrace like this nearly every time:

Call Trace:
 delay_tsc+0x4a/0x80
 __const_udelay+0x2c/0x30
 e1000_acquire_swflag_ich8lan+0xa2/0x240 [e1000e]
 e1000e_read_phy_reg_igp+0x29/0x80 [e1000e]
 e1000e_phy_has_link_generic+0x85/0x120 [e1000e]
 e1000_check_for_copper_link_ich8lan+0x48/0x930 [e1000e]
 e1000e_has_link+0x55/0xd0 [e1000e]
 e1000_watchdog_task+0x5e/0x960 [e1000e]

It hinted me to a problem in the e1000e Ethernet card module, and indeed a sudo rmmod e1000emade the high CPU load go away immediately [e1000e bug #26].

用户态进程：

可以使用kill -6 pid杀掉进程，产生一个core文件。多次执行后，基本上就能看出来哪段代码在占用cpu。