[ale] linux kernel tuneables ?

Gene Matthews gene at mmc-inc.com
Wed Dec 19 12:00:51 EST 2001


I have a client that is using tomcat and is getting messages indicating 
"too many files open".

So I'm trying to figure out what parms and how to change them.

Thanks, Chris for the info.

gene

jeff hubbs wrote:

> For enlightenment's sake, what kind of parameters do people modify and 
> under what circumstances?
> 
> - Jeff
> 
> Chris Ricker wrote:
> 
>> On Wed, 19 Dec 2001, Gene Matthews wrote:
>>
>>
>>> I am trying to figure out where I can tune certain things under 
>>> linux. Solaris has the /etc/system file where you set values for some 
>>> kernel parms that are pickep up at boot time.  I haven't found (yet) 
>>> anything similar, although I'm still looking.
>>>
>>> Can anyone point me in the right direction?
>>>
>>
>> Linux has two interfaces to the exact same kernel parameters, a BSD-sytle
>> sysctl(8) and /proc/sys.
>>
>> sysctl is a command to modify parameters.  It can be run directly with 
>> the
>> parameter to modify (similar to using adb / mdb on the running kernel in
>> Solaris), but more typically the parameters are listed in 
>> /etc/sysctl.conf
>> (similar to /etc/system).  sysctl -p will apply that file.
>>
>> /proc/sys contains files representing the tunable parameters.  Values 
>> are read by catting the files, and are changed by echoing new values 
>> into the files.
>>
>> The same parameters are available through either interface.  It's just 
>> a matter of which syntax you prefer.  For example,
>>
>> sysctl -w kernel.sysrq=1
>>
>> and
>> echo "1" > /proc/sys/kernel/sysrq
>>
>> both do the same thing -- enable the Magic SysRequest key.
>>
>> The files in
>> /usr/src/linux/Documentation/{networking/ip-sysctl.txt,sysctl/*} document
>> all the available parameters.
>>
>> later,
>> chris
>>
>>
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>>
> 
> 
> 
> 
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