Re: [hylafax-users] IRQ Overload

["Lee Howard" <lee.howard@xxxxxxxxxxxx>]

I've had numerous conversations with a few people regarding this topic...
Furthermore, I've done a lot of research on it... And I still don't know
for-certain what the problem is or how, exactly, to fix it.

What seems clear, however, is that there is a bug in the kernel serial
driver that is, for some reason, more prominent on newer kernel versions and
is, for some reason, more prominent when using high port-count IQ Express
fax cards (although there have been reports of this kind of thing using
other serial hardware and software).

There was a confirmed bug report with two patches from Robert Evans of
Stratus Technologies that circulated on the linux-serial mailing list on 13
August that dealt specifically with SMP systems.  (The systems on which I've
reproduced this problem have all been SMP.)  I do not know if the patches
were ever committed to the Linux kernel source repository - although one is
apparently in the RedHat 5.2 version - or if they will be making it in to a
subsequent kernel release.  Furthermore, I do not know if the patches will
resolve the matter.  (I have not tested them.)

http://article.gmane.org/gmane.linux.serial/2633

Mainpine has chosen to develop a work-around to the problem which won't be
available for another few weeks.  Please check back with me for updates on
that.  Meanwhile, I would suggest reporting a bug to the kernel maintainer
for your distribution.  Please do point them at the above-mentioned URL.
Hopefully they can provide you with a patched kernel which you could test.

Thanks,

Lee.

Lee Howard
Mainpine, Inc. Software Development Lead
Tel: +1 866 363 6680 ext 5 | Fax: +1 360 462 8160
lee.howard@xxxxxxxxxxxx | www.mainpine.com

-----Original Message-----
From: msbrentlinger@xxxxxxxxx [mailto:msbrentlinger@xxxxxxxxx] 
Sent: Friday, September 12, 2008 11:04 AM
To: Lee Howard
Cc: hylafax-users@xxxxxxxxxxx
Subject: Re: IRQ Overload


I have the same issue as well.. Did anyone ever come to some resolution to
this issue?

I have HylaFAX (tm) Version 5.2.7 from hylafax-5.2.7-1.fc9.i386.rpm
installed on Fedora release 9 (Sulphur) 2.6.25-14.fc9.i686 with a Mainpine
IQ Express 8-port (Low Profile) RF2123


at night we send a batch of anywhere from a few dozen to a few hundred
faxes, things start off fine and then.

/var/log/messages starts showing
Sep 11 20:33:10 hylafax kernel: serial8250: too much work for irq16 Sep 11
20:33:10 hylafax kernel: serial8250: too much work for irq16 Sep 11 20:33:10
hylafax kernel: serial8250: too much work for irq16 Sep 11 20:33:10 hylafax
kernel: serial8250: too much work for irq16 Sep 11 20:33:10 hylafax kernel:
serial8250: too much work for irq16 Sep 11 20:33:10 hylafax kernel:
serial8250: too much work for irq16 Sep 11 20:33:10 hylafax kernel:
serial8250: too much work for irq16 ...
...

shortly there after the remaining faxes that are queued up go out start
failing with' too many attempts to dial'.

Eventually things seem to resolve itself because in the morning things are
going fine again without any reboots or anything. Throughout the day we do
send occasional faxes, but maybe 2-3 at a time every 10 minutes or so...
Nothing like our larger night batches of a couple hundered that get queued
up all at once.





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