Re: sysctl -a is slow

jhell wrote:
> 
> On Mon, 20 Sep 2010 10:26, David Xu wrote:
> In Message-Id: <4C976F14.8000408_at_freebsd.org>
> 
>> jhell wrote:
>>> On 09/19/2010 09:28, David Xu wrote:
>>>> just typed sysctl -a on keyboard, and found it is slow, sometimes
>>>> it has been stuck for a few seconds, further studied,I found it is
>>>> stucked at sysctl kern.geom:
>>>>
>>>> %/usr/bin/time sysctl -a kern.geom
>>>> kern.geom.collectstats: 1
>>>> kern.geom.debugflags: 0
>>>> kern.geom.label.debug: 0
>>>> kern.geom.label.ext2fs.enable: 1
>>>> kern.geom.label.iso9660.enable: 1
>>>> kern.geom.label.msdosfs.enable: 1
>>>> kern.geom.label.ntfs.enable: 1
>>>> kern.geom.label.reiserfs.enable: 1
>>>> kern.geom.label.ufs.enable: 1
>>>> kern.geom.label.ufsid.enable: 1
>>>> kern.geom.label.gptid.enable: 1
>>>> kern.geom.label.gpt.enable: 1
>>>>        2.01 real         0.00 user         0.00 sys
>>>>
>>>> it seems it needs more than 2 seconds to complete.
>>>>
>>>
>>> A ktrace(1) and a kdump(1) of the resulting ktrace.out file would
>>> probably help here along with uname -a. Ive seen this happen once before
>>> but do not recall what caused it.
>>>
>>>
>>> Regards & good luck,
>>>
>>
>> Result is dumped here.
>> http://people.freebsd.org/~davidxu/sysctl_slow.txt
>> I think the culprit is sysctl kern.geom.confdot,
>> which does not appear in normal output, until I check the kdump result.
>> I tried five times, and it was blocked three times.
>>
> 
> 
> Inspecting the output of sysctl -b kern.geom.confdot will give you what 
> you currently have configured in the system as disks and what not 
> through geom. If this seems to be bailing at that point, which is an 
> opaque MIB/OID which doesn't come up other than when you use the "-o" 
> switch to sysctl(1) then could you check your labels for your disks for 
> any weird characters in the labels ?
> 
> ( sysctl -bo kern.geom )
> 
> Also does this have the same effect when run in a xterm, cons25 terminal ?
> 
> And same for the above but with the C, *_COUNTRY.UTF-8 or your normal 
> locale ?
> 
> ( env LANG=C sysctl kern.geom )
> 
> Looking at the output from mine there are quite a few unprintable 
> characters present. Maybe these are having an impact with one of your 
> labels.
> 
>

I redirect all output to a disk file, and it still needs 1 second to
complete, this machine is dual-core pentium E5500, faster than previous
one which is a dual-core AMD 5000+ machine, the 5000+ needs 2
seconds to complete.

$/usr/bin/time sysctl -b kern.geom.confdot > sysctl_geom_confdot.txt
         1.00 real         0.00 user         0.00 sys

the file is here:
http://people.freebsd.org/~davidxu/sysctl_geom_confdot.txt