kern/73744: printing via cups causes "Interrupt storm" warning, throttles output

Jin Guojun [VFFS] g_jin at
Fri May 6 19:50:07 PDT 2005

The following reply was made to PR kern/73744; it has been noted by GNATS.

From: "Jin Guojun [VFFS]" <g_jin at>
To: bug-followup at
Cc: bobf at
Subject: Re: kern/73744: printing via cups causes "Interrupt storm" warning,
 throttles output
Date: Fri, 06 May 2005 19:46:40 -0700

 This problem is still existing in 5.4-RC4.
 First I thought this my be related to APIC issue since one of my machine is
 ASUS P2B-DS (dual P-III), which is on the APIC blacklist, that has to 
 have APIC disabled.
 The other of machine is AMD XP, which is APIC enabled. So, it seems not 
 APIC related.
 Both machines experience this problem:
 stray irq7
 stray irq7
 Interrupt storm detected on "irq7: lpt0"; throttling interrupt source
 stray irq7
 stray irq7
 too many stray irq 7's: not logging anymore
 This is not just for CUPS. It is for lpr or any printing job sent to 
 parallel printers.
 The printer will still print, but it speed is about two lines per minute.
 lptcontrol -p /dev/lpt0
 does work in this problem.
 ------------ Jin Guojun -----------
 Distributed Systems Department
 Lawrence Berkeley National Laboratory,	Berkeley, CA 94720
 --------------- original message --------------------
 following a very recent portupgrade to RELEASE_5_3_0, printing via cups now causes the following error message to appear on the console:
 Interrupt storm detected on "irq7:lpt0": throttling interrupt source
 This caused printing to be GROSSLY unacceptably slow
 stopping cups, then using 'lptcontrol -p /dev/lpt0', then restarting it again worked around the problem and restored acceptable print performance.
 This is the first time I have seen this happen, and I have been printing on this machine for quite some time.

More information about the freebsd-bugs mailing list