Re: kapm-idled shows 90+% cpu usage when idle

Re: kapm-idled shows 90+% cpu usage when idle

[Mikael Pettersson]

On Thu, 9 Aug 2001 19:33:42 -0400, safemode <safemode@speakeasy.net> wrote:
>Is this a true usage reading or just some quirk that's supposed to happen?   
>I really doubt that this kernel daemon should really be using  cpu.  It seems 
>to respond with a higher cpu usage when i'm idle.  It immediately goes away 
>when something else uses cpu.   If you need any more info just ask.   I'm 

Do you have CONFIG_APM_CPU_IDLE=y in your .config? If so, disable it.

There was a thread about this problem some months ago. I found
that on all of my APM-capable machines, including a Dell laptop,
CONFIG_APM_CPU_IDLE=y had a negative effect. The kernel ended up
in a tight loop performing tons of APM IDLE BIOS calls, since each
BIOS call returned immediately without having idled the CPU.

Leaving CONFIG_APM_CPU_IDLE unset lets the kernel use its own
"HLT when idle" code. On my main development box, idle CPU
temperature dropped >10 degrees C, and kapm-idled now uses 0% CPU.

/Mikael

Re: kapm-idled shows 90+% cpu usage when idle

[safemode]

On Thursday 09 August 2001 20:36, Mikael Pettersson wrote:
> On Thu, 9 Aug 2001 19:33:42 -0400, safemode <safemode@speakeasy.net> wrote:
> >Is this a true usage reading or just some quirk that's supposed to happen?
> >I really doubt that this kernel daemon should really be using  cpu.  It
> > seems to respond with a higher cpu usage when i'm idle.  It immediately
> > goes away when something else uses cpu.   If you need any more info just
> > ask.   I'm
>
> Do you have CONFIG_APM_CPU_IDLE=y in your .config? If so, disable it.
>
> There was a thread about this problem some months ago. I found
> that on all of my APM-capable machines, including a Dell laptop,
> CONFIG_APM_CPU_IDLE=y had a negative effect. The kernel ended up
> in a tight loop performing tons of APM IDLE BIOS calls, since each
> BIOS call returned immediately without having idled the CPU.
>
> Leaving CONFIG_APM_CPU_IDLE unset lets the kernel use its own
> "HLT when idle" code. On my main development box, idle CPU
> temperature dropped >10 degrees C, and kapm-idled now uses 0% CPU.
>
> /Mikael

I've been told by others that this is exactly what's supposed to happen.  It 
acts like it's using cpu when it's idle and does it job that way.  I see no 
difference either way.   I'm using a KA7 motherboard and it says it supports 
apm and lspci shows what i pasted in the original post.  Oh well, it's not 
causing the cpu to generate more heat than it would be idle.  

Re: kapm-idled shows 90+% cpu usage when idle

[Mike Fedyk]

> > On Thu, 9 Aug 2001 19:33:42 -0400, safemode <safemode@speakeasy.net> wrote:
> > >Is this a true usage reading or just some quirk that's supposed to happen?
> > >I really doubt that this kernel daemon should really be using  cpu.  It
> > > seems to respond with a higher cpu usage when i'm idle.  It immediately
> > > goes away when something else uses cpu.   If you need any more info just
> > > ask.   I'm
> >

> On Thursday 09 August 2001 20:36, Mikael Pettersson wrote:
> > Do you have CONFIG_APM_CPU_IDLE=y in your .config? If so, disable it.
> >
> > There was a thread about this problem some months ago. I found
> > that on all of my APM-capable machines, including a Dell laptop,
> > CONFIG_APM_CPU_IDLE=y had a negative effect. The kernel ended up
> > in a tight loop performing tons of APM IDLE BIOS calls, since each
> > BIOS call returned immediately without having idled the CPU.
> >
> > Leaving CONFIG_APM_CPU_IDLE unset lets the kernel use its own
> > "HLT when idle" code. On my main development box, idle CPU
> > temperature dropped >10 degrees C, and kapm-idled now uses 0% CPU.
> >
> > /Mikael
> 

On Thu, Aug 09, 2001 at 10:01:55PM -0400, safemode wrote:
> I've been told by others that this is exactly what's supposed to happen.  It 
> acts like it's using cpu when it's idle and does it job that way.  I see no 
> difference either way.   I'm using a KA7 motherboard and it says it supports 
> apm and lspci shows what i pasted in the original post.  Oh well, it's not 
> causing the cpu to generate more heat than it would be idle.  

If you don't see any benefit, I'd disable it just because of the modified
results from top...

kapm-idled shows 90+% cpu usage when idle

[safemode]

Is this a true usage reading or just some quirk that's supposed to happen?   
I really doubt that this kernel daemon should really be using  cpu.  It seems 
to respond with a higher cpu usage when i'm idle.  It immediately goes away 
when something else uses cpu.   If you need any more info just ask.   I'm 
 
I'm using 2.4.8-pre7  
00:00.0 Host bridge: VIA Technologies, Inc. VT8371 [KX133] (rev 02)
00:01.0 PCI bridge: VIA Technologies, Inc. VT8371 [KX133 AGP] 
00:07.0 ISA bridge: VIA Technologies, Inc. VT82C686 [Apollo Super South] (rev 
22)
00:07.1 IDE interface: VIA Technologies, Inc. Bus Master IDE (rev 10)
00:07.4 Host bridge: VIA Technologies, Inc. VT82C686 [Apollo Super ACPI] (rev 
30)

I didn't see acpi in my motherboard manual at the time of configuring the 
kernel, should i be using the acpi idle daemon instead of the supposedly 
supported APM idle daemon?

Re: kapm-idled shows 90+% cpu usage when idle

[Erik Mouw]

On Thu, Aug 09, 2001 at 07:33:42PM -0400, safemode wrote:
> Is this a true usage reading or just some quirk that's supposed to happen?   

See http://www.tux.org/lkml/#s14-1


Erik

-- 
J.A.K. (Erik) Mouw, Information and Communication Theory Group, Department
of Electrical Engineering, Faculty of Information Technology and Systems,
Delft University of Technology, PO BOX 5031,  2600 GA Delft, The Netherlands
Phone: +31-15-2783635  Fax: +31-15-2781843  Email: J.A.K.Mouw@its.tudelft.nl
WWW: http://www-ict.its.tudelft.nl/~erik/