[PATCH] 2.4.2: cure the kapm-idled taking (100-epsilon)% CPU time

[PATCH] 2.4.2: cure the kapm-idled taking (100-epsilon)% CPU time

[Francis Galiegue]

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As attachment. Don't ask me why it works. Rather, if you see why it works, I'd
like to know why :)

Patch also applies cleanly over 2.4.2-ac10.

-- 
Francis Galiegue, fg@mandrakesoft.com - Normand et fier de l'être
"Programming is a race between programmers, who try and make more and more
idiot-proof software, and universe, which produces more and more remarkable
idiots. Until now, universe leads the race"  -- R. Cook

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--- linux/arch/i386/kernel/apm.c.old	Sat Mar  3 23:59:36 2001
+++ linux/arch/i386/kernel/apm.c	Sat Mar  3 23:57:56 2001
@@ -557,7 +557,7 @@
 {
 	u32	dummy;
 
-	if (apm_bios_call_simple(APM_FUNC_IDLE, 0, 0, &dummy))
+	if (apm_bios_call(APM_FUNC_IDLE, 0, 0, &dummy, &dummy, &dummy, &dummy, &dummy))
 		return 0;
 
 #ifdef ALWAYS_CALL_BUSY

Re: [PATCH] 2.4.2: cure the kapm-idled taking (100-epsilon)% CPU time

[Francis Galiegue]

On Sun, 4 Mar 2001, Francis Galiegue wrote:

> 
> As attachment. Don't ask me why it works. Rather, if you see why it works, I'd
> like to know why :)
> 

BTW, in case this matters, this is with gcc 2.95.3 compiler...

-- 
Francis Galiegue, fg@mandrakesoft.com - Normand et fier de l'être
"Programming is a race between programmers, who try and make more and more
idiot-proof software, and universe, which produces more and more remarkable
idiots. Until now, universe leads the race"  -- R. Cook

Re: [PATCH] 2.4.2: cure the kapm-idled taking (100-epsilon)% CPU time

[Alan Cox]

> As attachment. Don't ask me why it works. Rather, if you see why it works, I'd
> like to know why :)

Why are you breaking kapm-idled. It is supposed to take all that cpu time. You
just broke all the power saving

Re: [PATCH] 2.4.2: cure the kapm-idled taking (100-epsilon)% CPU time

[Francis Galiegue]

On Sat, 3 Mar 2001, Alan Cox wrote:

> 
> > As attachment. Don't ask me why it works. Rather, if you see why it works, I'd
> > like to know why :)
> 
> Why are you breaking kapm-idled. It is supposed to take all that cpu time. You
> just broke all the power saving
> 

Well, from reading the source, I don't see how this can break APM... What am I
missing?

-- 
Francis Galiegue, fg@mandrakesoft.com - Normand et fier de l'être
"Programming is a race between programmers, who try and make more and more
idiot-proof software, and universe, which produces more and more remarkable
idiots. Until now, universe leads the race"  -- R. Cook

Re: [kernel] Re: [PATCH] 2.4.2: cure the kapm-idled taking (100-epsilon)% CPU time

[Philipp Rumpf]

On Sun, Mar 04, 2001 at 12:19:07AM +0100, Francis Galiegue wrote:
> Well, from reading the source, I don't see how this can break APM... What am I
> missing?

apm_bios_call must not be called with two identical pointers for
two different registers.

Re: [kernel] Re: [PATCH] 2.4.2: cure the kapm-idled taking (100-epsilon)% CPU time

[Francis Galiegue]

On Sat, 3 Mar 2001, Philipp Rumpf wrote:

> > Well, from reading the source, I don't see how this can break APM... What am I
> > missing?
> 
> apm_bios_call must not be called with two identical pointers for
> two different registers.
> 

OK, my bad... By replacing the call I made with this:

        u32     dummy, a, b, c, d;

        if (apm_bios_call(APM_FUNC_IDLE, 0, 0, &dummy, &a, &b, &c, &d))
                return 0;

then the situation is back to "normal"...

Just one more thing though: in apm_bios_call_simple():

[...]
    APM_DO_SAVE_SEGS;
    {
        int cx, dx, si;
[...]

Aren't cx, dx and si really meant to be u32?

-- 
Francis Galiegue, fg@mandrakesoft.com - Normand et fier de l'être
"Programming is a race between programmers, who try and make more and more
idiot-proof software, and universe, which produces more and more remarkable
idiots. Until now, universe leads the race"  -- R. Cook

Re: [PATCH] 2.4.2: cure the kapm-idled taking (100-epsilon)% CPU

[Alan Cox]

> Well, from reading the source, I don't see how this can break APM... What=
>  am I
> missing?

If you've stopped kapm-idled from using cpu then you've stopped it from going
into the bios suspend one presumes.