Re: acpi breaks async interface

Pavel Machek (pavel@suse.cz)
Wed, 7 Feb 2001 11:45:05 +0100


Hi!

> I just found a strange thing in 2.4.1 (don't know, if the same
> occured in 2.4.0) and 2.4.1-ac3. When I enable ACPI, my serial
> port starts to drop some characters. When making ppp over this
> and doing ping, it causes great packet losts. If I turn ACPI in
> this configuration off, it works with no problems. I tried to
> switch serial port IRQ to other one (was 4, switched to 3 and
> tested) and it didn't help. Maybe something's broken.
>
> ACPI related boot messages:
>
> Feb 4 23:21:58 idoru kernel: ACPI: Core Subsystem version [20010125]
> Feb 4 23:21:58 idoru kernel: ACPI: Subsystem enabled
> Feb 4 23:21:58 idoru kernel: ACPI: System firmware supports: C2 C3
> Feb 4 23:21:58 idoru kernel: ACPI: System firmware supports: S0 S1 S4 S5
>
> [root@idoru log]# cat /proc/interrupts
> CPU0
> 0: 57278 XT-PIC timer
> 1: 2658 XT-PIC keyboard
> 2: 0 XT-PIC cascade
> 4: 49530 XT-PIC serial
> 5: 1 XT-PIC soundblaster
> 10: 15 XT-PIC aha152x
> 11: 60 XT-PIC eth0
> 12: 27772 XT-PIC PS/2 Mouse
> 14: 213118 XT-PIC ide0
> 15: 3298 XT-PIC ide1
> NMI: 0
> LOC: 0
> ERR: 0

ACPI slows down CPU quite a lot. Maybe cpu is so slow it can no longer
handle serial in time?

Try running

while(1);

program while doing serial transfers.
Pavel

-- 
I'm pavel@ucw.cz. "In my country we have almost anarchy and I don't care."
Panos Katsaloulis describing me w.r.t. patents at discuss@linmodems.org
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