setting cpu affinity for linux kernel, not process [closed]

Question

I am having a hard time finding information about how to set cpu affinity for linux kernel (with all of its loaded modules), NOT for a specific process.

This is because I want the kernel to run on CPU 0 all the time to handle I/O stuff, and not do any switches to run on other 3 CPUs because it may pollute L1 and L2 caches.

Thanks in advance.

Nulik

Fiddler

I believe it may already do this - at least interrupt handlers always seem to run on core 0. – Cinereous

I read in an article that kernel may run in different cores, and when I checked some source files there were many 'spin-lock' calls, i.e. it locks because the kernel code may be executed in parallel on different CPUs – Fiddler

@Nulik: System calls made by user threads will cause the kernel to run on many different cores. That's very different from parallel interrupt handling, though. – Outsoar

Do not know why the question is closed. Setting affinity has fully programming intention. Voted for reopen. – Portent

I don't think this is an off-topic question. – Sarre

Answer 1

Kernel work on behalf of processes will always happen on the CPU that makes the request. You can steer interrupts, though. Look at /proc/interrupts to identify the interrupts you want to move (say everything matching eth0) and set the affinity by echoing a hexadecimal mask to /proc/irq/XXX/smp_affinity.

Metacarpus

Answer 2

You should be able to disable the other cores via a kernel command-line option.

Not having the kernel run on a core implies that nothing else can run on that core either. No kernel scheduler and no TLB setup -> no code executing.

Outsoar