[hsflinux] Modem dropping connection under high CPU load

Linuxant support (Jonathan) support at linuxant.com
Mon Feb 14 11:33:54 EST 2005


since the HSF driver need to process should in real time and Linux is 
not a real time operating system, if you have a process which is 
attempting to use 100% CPU or IO usage that the connection might drop 
since the HSF driver can't process the signal in real time.

If you have such a process on your machine, please try to kill it to see 
if there is a difference. Another user reported in the past that this 
problem can also be related to your hard drive and DMA usage:

Problem solved. On the web I found out that I had to compile with
CONFIG_BLK_DEV_PIIX=y rather than as a module in order to use DMA disk
access. Now my disk access is sped up by a factor of 10 according to
hdparm tests, and my previous mouse/sound/modem problems seem to be solved.


Technical specialist / Linuxant
support at linuxant.com

Axel Müller wrote:
> Richard,
> I'm having the same problem using a Dell Inspiron 8200.
> Did you find a solution?
> Best regards,
> Axel
>> I have an HSF modem in a Dell Inspiron 5150 laptop and a registered 
>> copy of the modem drivers from Linuxant.
>> Everything works well apart from the modem will drop the line often 
>> when the CPU load is high. "High" can be anything from just surfing a 
>> few web sites to running a niced-down distributed application in the 
>> background.
>> This is with the latest HSF driver on the site. I'm tried this on an 
>> older kernel and a newer kernel and the results are about the same. 
>> I've tried tweaking every kernel parameter I can think of to improve 
>> matters but it makes no difference. I thought it may have to do with 
>> power management because the 5150 is notoriously bad at this. Anyway, 
>> I have the latest BIOS update from Dell on here too.
>> The following gets logged in /var/log/messages when a hangup is about 
>> to occur:
>> kernel: spurious 8259A interrupt: IRQ7.
>> kernel: Conexant: TX FIFO UNDERRUN (Bus Latency) - FIFOE
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