FBSD 7.1 & kern.maxdsiz

Jeremy Chadwick koitsu at freebsd.org
Wed Nov 19 08:42:00 PST 2008

On Wed, Nov 19, 2008 at 07:54:00AM -0800, Drew Tomlinson wrote:
> Jeremy Chadwick wrote:
>> On Wed, Nov 19, 2008 at 06:43:27AM -0800, Drew Tomlinson wrote:
>>> Mel wrote:
>>>> On Wednesday 19 November 2008 15:06:54 Drew Tomlinson wrote:
>>>>> Jeremy Chadwick wrote:
>>>>>> On Tue, Nov 18, 2008 at 04:10:55PM -0800, Drew Tomlinson wrote:
>>>>>>> Polytropon wrote:
>>>>>>>> On Tue, 18 Nov 2008 15:34:32 -0800, Drew Tomlinson          
>>>> <drew at mykitchentable.net> wrote:
>>>>>>>>> The Urchin installation docs [...]
>>>>>>>>> contain a note for FreeBSD users waring of a "hard coded process
>>>>>>>>> datasiz limit of 500 MB" and instruct on to set
>>>>>>>>> "kern.maxdsiz="1073741824"" in /boot/loader.conf.  However FBSD 7.1
>>>>>>>>> doesn't appear to have this sysctl.  How can I do the equivalent of
>>>>>>>>> this in FBSD 7.1?
>>>>>>>> Exactly, it is *not* a sysctl setting. It's a loader tunable, as
>>>>>>>> I learned from this list some time ago. Don't search to find
>>>>>>>> it in the sysctl list, you won't find it there. :-)
>>>>>>>> In FreeBSD 7 you should be able to set this setting using
>>>>>>>> the file /boot/loader.conf. I think I had this setting on a
>>>>>>>> FreeBSD 5 machine, I'll go and check.
>>>>>>> Thanks for your reply.  I guess I expected to be able to view it via
>>>>>>> sysctl even though I understood it could only be changed with a reboot.
>>>>>>> Is there some way to view the current setting?
>>>>>> Through sysctl.
>>>>> OK, what am I missing?
>>>>> urchin# sysctl -a | grep maxdsiz
>>>>> compat.ia32.maxdsiz: 536870912
>>>>> compat.linux32.maxdsiz: 536870912
>>>> limits -H. Some loader tuneables aren't exported to sysctl.
>>>> $ limits -Hd
>>>> Resource limits (current):
>>>>   datasize           786432 kB
>>>> $ grep maxdsiz /boot/loader.conf
>>>> kern.maxdsiz="768M"
>>> Thanks for the explanation!  As pointed out by Pieter de Goeje, the   
>>> default size in FBSD 7 amd 64 is 32 GB, confirmed with the limits   
>>> command above.  Thus datasize does not appear to be my problem.  I'm  
>>> shooting in the dark here as Urchin software support is non-existent. 
>>>   Are there any other tuneables related to datasize that I might try  
>>> increasing?
>> It would help greatly if you could explain what the problem is that
>> you're trying to track down?
> I understand I'm asking for "magic".  I do not know the problem.  My  
> employer's Internet group purchased a software called "Urchin" which  
> appears to be a standalone version of Google Analytics for web site  
> reporting.  I have been tasked with installing this software.  Supported  
> OSs are Linux, FreeBSD, and Windows.  I chose FreeBSD 7 as I've been  
> using it for my home network for years.  However I will be the first to  
> admit that I do not really understand the internals.  I am just grateful  
> that others that do understand have provided and support this OS for me.  
> :)
> The Urchin software reports a "failed to allocate memory" error.  The  
> sparse Urchin documentation noted above says this error is a known issue  
> with FreeBSD and that kern.maxdsiz needs to be set at 1 GB to avoid.   
> Because of help from the list, I learned that the default size in 64 bit  
> FBSD is 32 GB.  Thus I didn't think this is my issue and was seeking any  
> ideas of what else to look at that might be similar.  Mel gave me a  
> great nudge that if Urchin is a 32 bit binary (which it is), then it is  
> limited by compat.ia32.maxdsiz which is 500 MB by default.  I have set  
> this to 1GB and so far, there have not been any further memory errors.

I believe Mel's recommendation is spot on.  I had no idea this was a
32-bit binary being run on a 64-bit version of FreeBSD.  So yes, the
tunable he gave you should fix the problem.  :-)


| Jeremy Chadwick                                jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |

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