ksoftirqd

[James Wilkinson]

J.L. Coenders wrote:
> While transferring some data to my usb disk ksoftirqd went beserk and locked 
> up almost the entire machine. The only thing I could do was close it.
> Anyone know if this is 'default' behaviour for heavy file transfers? Or might 
> it be another problem?

Well, it certainly is a problem.

ksoftirqd is part of the kernel. As I understand it, when hardware
wants to get the kernel's attention (or vice versa), an interrupt
("IRQ") is raised. The kernel does the bare minimum necessary to
acknowledge the interrupt, then punts the rest of the necessary
processing to ksoftirqd. This means that having lots of interrupts
generates lots of ksoftirqd activity.

But having that many isn't normal, and could well indicate a hardware
problem. Try the disk on another computer, or try a different kernel,
and see what happens.

It would also be helpful to know:
 * whether you're using "Hi-Speed" (480 Mb/s) or "Full Speed" (12 Mb/s)
   ( http://www.everythingusb.com/usb2/faq.htm ). If either end is
   USB 1 only, you're on 12 Mb/s.
 
 * whether your "disk" is based on flash memory, a traditional hard
   disk, or some sort of removable media (e.g. Zip).

 * The model and make of your disk and motherboard.

 * Whether you've got anything else on that USB bus.

Hope this helps,

James.

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