MYSTERY: APM monitors kill PPP throughput

MYSTERY: APM monitors kill PPP throughput

Post by Nathan Mye » Tue, 20 Oct 1998 04:00:00



I'm running kernel 2.1.125 on a K6.  When I run the Gnome "panel" with
the battery-charge monitor applet, it kills my PPP throughput; ifconfig
reports frequent framing errors.  Other battery-charge monitors
(e.g. wmapm) cause somewhat less trouble.  The effect is quite
repeatable.  It's a mystery to me how this is possible, or
preventable.  Clues?

--
Nathan Myers

 
 
 

MYSTERY: APM monitors kill PPP throughput

Post by Andi Klee » Tue, 20 Oct 1998 04:00:00



> I'm running kernel 2.1.125 on a K6.  When I run the Gnome "panel" with
> the battery-charge monitor applet, it kills my PPP throughput; ifconfig
> reports frequent framing errors.  Other battery-charge monitors
> (e.g. wmapm) cause somewhat less trouble.  The effect is quite
> repeatable.  It's a mystery to me how this is possible, or
> preventable.  Clues?

The gnome module regularly asks the apm driver for the battery status.
The apm module disables interrupts while it calls into the APM BIOS.
If your APM bios is slow interrupts are disabled for a long time and then
serial interrupts are delayed until the fifo of the serial UART overflows -
result is framing errors.

-Andi

 
 
 

MYSTERY: APM monitors kill PPP throughput

Post by Jonathan Buzza » Tue, 20 Oct 1998 04:00:00





>> I'm running kernel 2.1.125 on a K6.  When I run the Gnome "panel" with
>> the battery-charge monitor applet, it kills my PPP throughput; ifconfig
>> reports frequent framing errors.  Other battery-charge monitors
>> (e.g. wmapm) cause somewhat less trouble.  The effect is quite
>> repeatable.  It's a mystery to me how this is possible, or
>> preventable.  Clues?

> The gnome module regularly asks the apm driver for the battery status.
> The apm module disables interrupts while it calls into the APM BIOS.
> If your APM bios is slow interrupts are disabled for a long time and then
> serial interrupts are delayed until the fifo of the serial UART overflows -
> result is framing errors.

How often is often? My work on Toshiba's would indicate that once every
three or four seconds is more than adequate. Put another way Toshiba's
battery monitoring utilities only inquire of the battery status every
three or four seconds, and Toshiba know a thing or two about laptops.

JAB.

--

Northumberland, United Kingdom.       Tel: +44(0)1661-832195

 
 
 

MYSTERY: APM monitors kill PPP throughput

Post by Nathan Mye » Tue, 20 Oct 1998 04:00:00






>>> I'm running kernel 2.1.125 on a K6.  When I run the Gnome "panel" with
>>> the battery-charge monitor applet, it kills my PPP throughput; ifconfig
>>> reports frequent framing errors.  Other battery-charge monitors
>>> (e.g. wmapm) cause somewhat less trouble.

>> The gnome module regularly asks the apm driver for the battery status.
>> The apm module disables interrupts while it calls into the APM BIOS.
>> If your APM bios is slow interrupts are disabled for a long time and then
>> serial interrupts are delayed until the fifo of the serial UART overflows -
>> result is framing errors.

>How often is often? My work on Toshiba's would indicate that once every
>three or four seconds is more than adequate. Put another way Toshiba's
>battery monitoring utilities only inquire of the battery status every
>three or four seconds, and Toshiba know a thing or two about laptops.

Evidently the Gnome monitor checks a lot more often.  It seems to me
that once a minute would be good enough.  Anyway, different laptops have
different latencies for this operation; evidently recent Mitac systems
have really, really slow APM functions.  I would rather not miss *any*
interrupts, and so have given up on running battery monitors on my
machine.

--
Nathan Myers

 
 
 

1. PPP throughput monitor, setup hints

Can anybody recommend a nice X-based utility for monitoring throughput
on a PPP or SLIP connection?  I'd be particularly interested with any
sort of meter or graph kind of thing that dynamically shows the max and
current throughput.

I'm working with a bunch of new hardware and also with SLIP and PPP on
Linux for the first time.  I have some concerns/suspicions about my
modem setup and my PPP configuration.  And, of course, we all want to
pump as many bytes through our modems as possible.  So, any other tuning
hints would also be welcome.

Thanks.

-Dave


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