Re: modem <-> performance weirdness
On Mon, Sep 09, 2002 at 06:35:32PM +0200, martin f krafft wrote:
> i have an old 486DX2-66. it happily does pppoe/pppd + iptables
> MASQUERADE + bind9 + dhcpd for my home network all day long. it's
> system load usually doesn't exceed 0.20. it's running sarge with
> a custom 2.4.18 kernel.
>
> there's also a modem connected to the machine on ttyS0, linked to
> /dev/modem, simply because i need to establish some non-ISP PPP
> connections with the outside world and send faxes.
>
> here's a problem that baffles me:
>
> when i use /usr/bin/pon or minicom to simply dial out to another
> modem where there's a pppd+mgetty waiting to accept calls, the
> system goes gaga. with that i mean this:
> - as soon as the connection is started (i.e. the modem screams),
> the system load just keeps climbing. i just had it at 76.00.
> - i can't see the top output, because top doesn't update anymore
> - the entire system is unresponsive
> - only when i physically turn off the modem, then the computer
> goes back to normal
>
> i have experimented with the above to a point where i've disabled
> as many processes as possible, and then tried again. but even with
> only 14 processes running, the same happens.
>
> how should i go from here? what can i try to narrow in on the problem?
I never used it but:
# apt-get install hwtools
$ cd /usr/share/doc/hwtools/
$ links irqtune.html # lynx
irqtune changes the IRQ priority of devices to allow devices that
require high priority and fast service (e.g. serial ports, modems) to
have it.
With irqtune, a 3X speedup of serial/modem throughput is possible.
--
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Osamu Aoki @ Cupertino CA USA, GPG-key: A8061F32
.''`. Debian Reference: post-installation user's guide for non-developers
: :' : http://www.debian.org/doc/manuals/reference/ also http://qref.sf.net
`. `' "Our Priorities are Our Users and Free Software" --- Social Contract
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