[LON-CAPA-admin] server load

[Stefan Bisitz]

Hi James,

Some additional notes:

There could be different reasons for a high server load. A simple one 
could be to have not enough memory (RAM) in the server while many 
students are working at the same time.

The server automatically offloads (if available) to other access servers 
when users try to login and the server load exceeds 100%. Some functions 
are temporarily disabled, too, e.g. student progress chart.

The displayed value for "server load" is the load value seen when using 
top, as Mark wrote, related to the specified value for lonLoadLim in 
loncapa.conf. Default is 2.00. Example: configured load limit is 2.00, 
current value is 0.10 -> server load: 0.10/2.00 = 0.05 -> 5%

The user load limit needs also to be configured. Default is 0 which 
means not active.

To change the values, loncapa.conf (/etc/httpd/conf/loncapa.conf) needs 
to be updated. The administrator is offered to change these values when 
LON-CAPA is first installed or when upgraded. The changes are written to 
loncapa.conf.

I am seeing an old LON-CAPA release for the sc domain. The current 
release 2.10.1 does suppress the user load if not active. If the value 
for lonUserLoadLim in loncapa.conf is 0, no actual user load is measured 
and is always displayed as 0 in old releases.

Stefan Bisitz


Am 26.10.2012 15:57 schrieb Lucas, Mark:
> The server load is the system load average multiplied by 100.
>
> If you use the top command you can see the load average at the top of the screen and you
> may also gain some insight into the process or processes that are taking up CPU time.
>
> There may be a background job running. You may also have some other 'runaway' process.
> When I am running backups on a machine, the system load goes up even though the user
> load is minimal.
>
> Mark
>
> On Oct 26, 2012, at 9:50 AM, James Clawson wrote:
>
>> On our log in screen there is a bit of information
>>
>> Domain: sc
>> Server: sca1 (access)
>> Server Load: 52.5%
>> User Load:  0.00%
>>
>> What do the "loads" actually measure.
>> Why would the server load be so high on this machine (when the user load
>> seems to be 0%)?  I have seen in up in the 80% range before
>>
>> Our other access server does not show this at the same time.  The
>> library server shows 9.5% server load @ 0% user load.
>>
>> Just trying to get a fix on some quick and dirty diagnostics.
>>
>> Thanks
>> James
>>
>> --
>> James Clawson, Jr.
>> Laboratory Manager
>> University of South Carolina
>> Department of Physics and Astronomy
>> Jones PSC Room 402D
>> 803-777-8994
>>
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>