kern/104406: [ufs] Processes get stuck in "ufs" state under persistent CPU load

Kris Kennaway kris at
Wed Oct 31 14:44:37 PDT 2007

Rainer Hurling wrote:
> Thanks for your answer.
> Kris Kennaway schrieb:
>> Rainer Hurling wrote:
>>> Looking into PR kern/104406 it seems, that this describes exactly 
>>> what I am experiencing on three of my systems over the last weeks. 
>>> They are running FreeBSD 8.0-CURRENT (known as 7.0-CURRENT not long 
>>> ago ;-) ).
>> Actually it sounds nothing like it at all ;)
>>> On these machines I often observe hangings, sometimes only a few 
>>> seconds, on other times 20-30 seconds before input/output is back. 
>>> This seems to happen when more extensive disk usage is needed 
>>> (portupgrade, buildworld, browsing complicated websites etc.). During 
>>> the hang even xterm is not responding any more, other (diskless) 
>>> applications like xclock keep to continue. I have no panics, only UFS 
>>> (and MSDOSFS) are mounted, no NTFS. About two months ago none of my 
>>> systems showed these hangings.
>> Is your system swapping?  This is the usual cause of pauses during 
>> high application (actually memory) load.
>> Kris
> No, I am working with 2GB RAM, without swapping at all.
> In the meantime I tested the above described behaviour a little more. 
> The hangings even appeared without using Xorg, only working on consoles 
> under heavy disk usage (portupgrade etc.).

OK, configure the system with the debugger and when it is "hung", break 
to DDB and obtain the data requested in the developers handbook to try 
and investigate what is going on.  You may want to do this a few times 
to make sure you capture a representative sample.


More information about the freebsd-stable mailing list