Date: Thu, 10 Nov 2005 12:59:22 -0500
To: Chip Salzenberg <chip@pobox.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: hostap interrupt problems, maintainers unresponsive - "wifi0: interrupt delivery does not seem to work"
Message-ID: <20051110175922.GB9632@delft.aura.cs.cmu.edu>
Mail-Followup-To: Chip Salzenberg <chip@pobox.com>,
	linux-kernel@vger.kernel.org
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From: Jan Harkes <jaharkes@cs.cmu.edu>
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On Wed, Nov 02, 2005 at 09:46:39AM -0800, Chip Salzenberg wrote:
> Hostap 0.4.4-kernel, included with kernel 2.6.14, does not work; nor
> do versions 0.3.9 nor 0.4.1 compiled separately against 2.6.14.  There
> seems to be a problem with interrupt delivery.  Soon after the module
> is installed, keystrokes and all other interrupt-driven activity pause
> periodically for a LONG time (on the order of five seconds).

I am seeing similar interrupt problems, but I don't have hostap (or even
a wireless network card) on my machine. For me a clear indication is the
serial port overrun errors even though that port only gets a handful of
interrupts per second from an attached GPS receiver. Under X, keyboard
and mouse are occasionally very jerky and unreponsive.

I just rebooted with 'acpi=noirq', and I'm not seeing the serial port
overrun errors anymore, it seems to have fixed, or at least mitigated
the problem a bit. But I'm logged into the machine remotely at the
moment, so I can't be sure if it really fixed the unresponsive
keyboard/mouse issues. There are a bunch of differences in the kernel
log, but one that was quite noticable was the estimated CPU speed and
that the IO-APIC seems to be intialized differently.

booting 2.6.14
--------------
Nov 10 09:49:23 thegate kernel: 247 MHz processor.

booting 2.6.14 with acpi=noirq
------------------------------
Nov 10 12:36:08 thegate kernel: Detected 2807.302 MHz processor.


It actually looks like there is a whole bunch of interesting information
from the early boot that got scrolled out of the printk buffer by the
time klog dumps everything to kern.log. I guess I should rebuild my
kernel with a larger ringbuffer.

Jan

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