Slapd Analysis with load

After having a look at the general performance in SlapdAnalysis, this page presents the same tests but putting additional load to the machine. The idea is to find out, how far the Slapd performance is affected by this load.

Generating the load scenarios

Load on a Grid CE Element
Some sites run a GIIS (BDII, but on site-level) on a Grid CE (Computing Element). To elemulate this concurrent cpu load, we take simple scripts doing some noops which are started with nice (see http://linux.about.com/library/cmd/blcmdl1_nice.htm ) with different process priorities. The stress tool (see http://weather.ou.edu/%7Eapw/projects/stress ) is used to generate either high CPU load or high I/O load.

The test script:

#!/bin/bash
while [ 1 ] ; do
 echo "" > /dev/null
done
started on the slapd machine with
nice -n 0 ./load_cpu

Test with Script

The graphs below show the average time a request takes to be processed. The left graph is the time/requests relation, the right one the timeout/request relation. Each scenario (with/without load) was done for 4 cycles each represented by one line in the graph.
With Load
The context switching of the scheduler obviously has a massive effect on the slapd. We see that timeouts even occur with already 50 (!) parallel requests. But below this, the response time for a request decreases.

370K_requesttime_load.png 370K_requesttimeout_load.png

Comparison without Load
Stable answer times for the requests and no timeouts.

370K_requesttime.png 370K_requesttimeout.png

-- FelixNikolausEhm - 01 Mar 2007

Topic attachments
I Attachment History Action Size Date Who Comment
PNGpng 370K_requesttime.png r2 r1 manage 2.5 K 2007-03-01 - 10:56 FelixNikolausEhm  
PNGpng 370K_requesttime_both.png r1 manage 3.3 K 2007-03-01 - 17:25 FelixNikolausEhm  
PNGpng 370K_requesttime_load.png r1 manage 3.0 K 2007-03-01 - 11:08 FelixNikolausEhm  
PNGpng 370K_requesttimeout.png r3 r2 r1 manage 1.8 K 2007-03-01 - 10:59 FelixNikolausEhm  
PNGpng 370K_requesttimeout_load.png r1 manage 2.5 K 2007-03-01 - 11:09 FelixNikolausEhm  
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Topic revision: r5 - 2007-05-14 - FelixNikolausEhm
 
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