Re: [offtopic?] process cpu load % wrong?

Ingo Molnar (mingo@pc7537.hil.siemens.at)
Thu, 16 Oct 1997 14:03:05 +0100 (MET)


On Thu, 16 Oct 1997, Tuukka Toivonen wrote:

> When I run some normal programs that don't use too much hard disk, the mp3
> player process stays at 25%-32%. But when I run some specific tasks, the
> mp3 cpu load increases to 60% or even more!

if you have IDE disks, PIO mode, then this is natural. Always the current
process handles interrupts, no matter who requested that interrupt. It
will be accounted to the handling process. So if you have a process that
generates only disk-IO, but does not use the CPU otherwise, the kernel
will switch to other processes while the interrupt is pending, and that
other process will handle the interrupt.

since interrupts cannot easily be 'personalized' (externally triggered
interrupts have no 'owners', and there are interrupts that have many
'owners', etc.), there is no easy 'solution'.

"It's Just Statistics."

-- mingo