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SubjectRe: [linux-usb] Re: Irq context wrong for USB ACM serial driver calling PPP?
On Tue, Mar 07, 2000 at 01:25:18AM +0100, Jamie Lokier wrote:

> > Wet string? Could you describe the problem better? I'd like to know if
> > there's anything wrong with ACM ... Pavel has reported massive system
> > slowdown with using JE's UHCI (due to bandwith reclamation), is it
> > that?
> Bandwidth reclamation is turned off, but I am using JE's UHCI. My
> system seems ok, it's just the modem connection that's slow.
> The TCP session is very conditional. Press a key, wait 5 seconds for
> display update. Here are some ping times. It could be my ISP today, or
> maybe the LAN at the far end is overloaded today.
> I only noticed since I went from 2.3.40 to 2.3.49 recently.
> 64 bytes from xx.xx.xx.xx: icmp_seq=10 ttl=241 time=270.0 ms
> 64 bytes from xx.xx.xx.xx: icmp_seq=11 ttl=241 time=730.0 ms
> 64 bytes from xx.xx.xx.xx: icmp_seq=12 ttl=241 time=300.0 ms
> 64 bytes from xx.xx.xx.xx: icmp_seq=13 ttl=241 time=320.0 ms
> 64 bytes from xx.xx.xx.xx: icmp_seq=14 ttl=241 time=760.0 ms
> 64 bytes from xx.xx.xx.xx: icmp_seq=15 ttl=241 time=540.0 ms

Well, this looks like a lightly loaded modem connection. Could you
please make sure the modem isn't used for anything but the ping
and ping the opposite point of the link only?

Btw, there were no important changes between 2.3.40 and 2.3.49 in acm.c
that could be causing this (except to the wakeup stuff now, which could
delay data by up to 10 ms).

Vojtech Pavlik
SuSE Labs

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