[Building Sakai] Strange load testing results

[Remi Saias]

Hello all,

In the past weeks I have been performing some load tests on our 
Sakai+OpenSyllabus server at HEC Montreal as we are planning to go live 
for a pilot project in January.

I used The Grinder which I found very efficient and easy to use, 
considering that OpenSyllabus is strongly dependent on Ajax requests and 
for this reason I could not use more classic tools relying on defined 
pages with fixed URLs etc.

I tested various configurations with a single scenario and was very 
surprised to find out that our development laptops (regular laptops with 
a CoreDuo under XP Pro) were running twice as fast as our linux server 
which has 4 Xeon CPU at 2.8Ghz. In each case the database server (mySQL 
4 and 5, tested both) was running on the same machine.

As I suspected something was incorrectly configured on the linux server, 
I tried it at home on a less powerful linux box (Dual Core 3Ghz vs Quad 
Xeon) and, surprise, I got a performance 4 times better. I used the 
exact same set of sakai tools, sakai version and tomcat version.

I am still investigating this but I am starting to run out of ideas! I 
have read confluence and added query caching (as per 
http://confluence.sakaiproject.org/display/DOC/MySQL+Administration 
<http://confluence.sakaiproject.org/display/DOC/MySQL+Administration>), 
but it didn't change anything at all. I tried tweaking various mySQL 
parameters without much impact!

Does this ring a bell to someone!? I have not yet investigated the 
server OS/hardware configuration (maybe the disk setup, raid or such...) 
but I thought that it might be faster to simply ask! :-)

BTW, Sakai 2.6.0 was 20% faster than 2.5.x in my tests.

Thanks for any help!

-- 
Rémi Saïas
Analyste en informatique - Technopédagogie
Gestion des technologies de l'information - HEC Montréal
Projet Sakai-OpenSyllabus: 514.340.6776 - Édifice Decelles: 4521 


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