What is CPU soft lockup?

What is CPU soft lockup?

A soft lockup is the symptom of a task or kernel thread using and not releasing a CPU for a longer period of time than allowed. The technical reason behind a soft lock involves CPU interrupts and nmi-watchdog. For each online CPU on the system, a watchdog process gets created.

How do I fix kernel NMI watchdog bug soft lockup?

To resolve this behavior, perform the following steps as root user:

1. Edit the file ‘/etc/sysctl.conf’ and add the following line at the end. “kernel.watchdog_thresh=30”
2. Save and Exit.
3. Reboot machine.

What is watchdog_thresh?

The watchdog task is a high priority kernel thread that updates a timestamp every time it is scheduled. The period of the hrtimer is 2*watchdog_thresh/5, which means it has two or three chances to generate an interrupt before the hardlockup detector kicks in.

What is a Kworker process?

“kworker” is a placeholder process for kernel worker threads, which perform most of the actual processing for the kernel, especially in cases where there are interrupts, timers, I/O, etc. These typically correspond to the vast majority of any allocated “system” time to running processes.

What is Ksoftirqd?

A ksoftirqd is a per-CPU kernel thread raised to handle unserved software interrupts: In the preceding top sample from my personal computer, you can see ksoftirqd/n entries, where n is the CPU number that the ksoftirqds runs on.

What is the purpose of Kthreadd?

kthreadd() is main function (and main loop) of daemon kthreadd which is a kernel thread daemon, the parent of all other kernel threads. So in the code quoted, there is a creation of request to kthreadd daemon. To fulfill this request kthreadd will read it and start a kernel thread. Then it will change the flag.

What is Kthreadd?

kthreadd is actually the internal kernel thread that is used in kernel code with functions like kthread_create() to create these kernel threads or adopt them.

What is Irqbalance Linux?

irqbalance is a Linux daemon that distributes interrupts over among the processors and cores in your computer system. The design goal of irqbalance is to do find a balance between power savings and optimal performance. This allows a given set of CPU’s to not be bothered by any interrupt service load.

Is a BSOD a kernel panic?

A kernel panic, or its equivalent in the Windows world of a stop error or the dreaded Blue Screen of Death (BSOD), happens as the result of an unspecified low level error that an operating system cannot recover from.