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  From: Alan Kennington <akenning@topology.org>
  To  : Tim Fairchild <tim_fairchild@bigpond.com>
  Date: Fri, 1 Jun 2001 15:11:03 +0930

Re: kapm-idled?

On Fri, Jun 01, 2001 at 02:53:47PM -0400, Tim Fairchild wrote:
> 
> I've been looking in the docs to no avail, but what exactly is the kapm-idled 
> process?  Not sure what it does, but it seems to chew large chunks of cpu 
> when the pc is sitting there doing apparently nothing.
> 
> running MDK8.0 kernel 2.4.3


Tim,

I don't know.
But it's on SuSE 7.1 too, and "apm" has to do with
power management.
Even though the price is not niced, it does get out of the way when
you run pretty much anything else - probably because the
kernel scheduling algorithm thinks that a process that uses 60% of
CPU cycles probably deserves a low dynamic priority.

Likewise, I can't find any documentation on the thing.
On the other hand, I found this in my
/usr/share/doc/packages/kapm/README file:

======================================================
  KAPM is a docking KDE utility that allows you to monitor your laptop's
  battery status and perform other APM (advanced power management)
  tasks.  
======================================================

Methinks this has nothing to do with it though.

Since kapm-idled runs as process number 3, and kswapd runs at 4,
the k must mean kernel.
So a reading of the "init" sources should reveal all.

  PID USER     PRI  NI  SIZE  RSS SHARE STAT %CPU %MEM   TIME COMMAND 
    1 root       8   0    76   64    44 S     0.0  0.0   0:04 init
    2 root       9   0     0    0     0 SW    0.0  0.0   0:00 keventd
    3 root      20   0     0    0     0 SW   36.7  0.0 25376m kapm-idled
    4 root       9   0     0    0     0 SW    0.0  0.0   3:16 kswapd
    5 root       9   0     0    0     0 SW    0.0  0.0   0:00 kreclaimd
    6 root       9   0     0    0     0 SW    0.0  0.0   1:04 bdflush
    7 root       9   0     0    0     0 SW    0.0  0.0   1:10 kupdated
    8 root      -1 -20     0    0     0 SW<   0.0  0.0   0:00 mdrecoveryd
    9 root       9   0     0    0     0 SW    0.0  0.0   0:00 kreiserfsd        

The /usr/src/linux/Documentation/pm.txt gives little enlightenment
on this, although you would expect it to.

++++++++++++++++++++++++++++++++++++++++++++++++++++
I've found it.
It's in /usr/src/linux/arch/i386/kernel/apm.c

=====================================================
static int apm(void *unused)
{
        unsigned short  bx;
        unsigned short  cx;
        unsigned short  dx;
        int             error;
        char *          power_stat;
        char *          bat_stat;

        kapmd_running = 1;

        daemonize();

        strcpy(current->comm, "kapm-idled");
        sigfillset(¤t->blocked);
        current->tty = NULL;    /* get rid of controlling tty */         
[....]
=====================================================

So it _is_ in the kernel.
Now the only question is how to control the thing.
But it's obvious why the kapm-idled doesn't appear
as an executable anywhere. It's just copied to the
command line area by the process itself.

Cheers,
Alan Kennington.

-- 
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