[K12OSN] TuxMath test on 8 core machine with teamed NICs 16GB RAM

Thu Dec 6 14:53:52 UTC 2007

Bad stats, Jim. That's not good news as everyone I see whose seen
tuxmath goes ape over it (especially the kids).

The version that ships with K12LTSP is a bazillion years old (the
abandoned version). The new version is 1.5.8 (tux hides in igloos and
cities are not destroyed, includes "lessons" and does negative
numbers!).

The code is essentially unchanged at the base level (SDL is an easy
cross platform toolset but is very inefficient). I don't have access to
a large client count at the moment but I'll check the new version vs.
the old version on Opteron systems ASAP. 

I'm really floored that the hardware you threw at this test choked so
badly. I suspect that the different memory management processes between
Opteron and Xeon will show up here (my testing last year showed an
average performance boost of 30+% in thin client speed between Opteron
and Xeon - Simultaneous launch of 24 OOo instances took 65 seconds on
Xeons and 42 seconds with freshly booted servers and client. Speed up
was even more dramatic with cached copy).

On Thu, 2007-12-06 at 09:31 -0500, Jim Kronebusch wrote:
> Well, as promised, I did a test yesterday afternoon to see how well TuxMath will scale
> on my hardware/network.  To review I have a dual quad core 2.66Ghz Xeon box (8 cores), 6
> 300GB SAS drives in RAID10, 16GB RAM, and 6 GB nics teamed with adaptive load balancing.
>  The the network is configured there are about 15-20 machines per GB connection to the
> server.  This is also running Edubuntu 7.04 with LDM_DIRECTX=true (no encryption) and
> the linux-image-server kernel under 32-bit to recognize the added RAM.
> 
> So I set out yesterday to see how well my setup would run TuxMath on 30 clients
> simultaneously......not good.  I started up 10, things looked great, CPU load averages
> under 10% and RAM under 2 GB.  Then I started 10 more, CPU under 25% (starting to get
> high), RAM under 3GB, and still moving at a decent speed and loading quickly.  Then I
> started 10 more, all hell broke loose :-(  My CPU average started climbing drastically,
> the server came to a halt, all the clients that were running slowed way down, I couldn't
> quit any instance of TuxMath.  The clients would respond to the point of exiting the
> game, then clicking quit, but the app stayed open and would not close.  My CPU average
> climbed to 148% (Not sure how that is possible) with all instances of TuxMath at the
> quit screen.  So even with all instances of TuxMath no longer moving graphics, but just
> sitting at the quit screen, my processor use still kept climbing, while RAM usage was
> still under 4GB.  The only way I could get the system to recover was by killing all
> instances of TuxMath.
> 
> So, I don't think all the problems users are seeing with TuxMath are related to network
> issues.  It appears 15 or so instances of TuxMath on a single machine are the max due to
> escalating processor usage.  The usage seemed to grow exponentially over time with the
> same amount of instances running.  And once overloaded, the system can't recover, even
> when there are no more moving graphics.  And given my system can handle 75 simultaneous
> Firefox sessions with Flash while switching back and forth to OpenOffice (on-line games
> until the teacher walks by) without breaking a sweat at 1280x1024 resolution, I'd
> venture to say the limitation is in the TuxMath code.
> 
> Another note, I also noticed for every workstation 3 instances of TuxMath showed up in
> htop, and two of those processes were under 1% of usage, while the third sucked all the
> power, maybe this is a hint to what is going on.  In this lab there are also 30
> machines, 15 on one 1GB connection, and 15 on another.  So I'm fairly certain network
> load was never an issue, all problems seem to point to excessive draw on CPU cycles.
> 
> No offense meant here to the programmers of TuxMath, it is great software and my kids
> love it.  I just hope this sheds some light on what is happening in a multiuser environment.
> 
> If anyone else has some suggestions on something to try, let me know.  It may take a few
> days to get the lab free and test, but I'll test it.
> 
> Jim
> 
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-- 
James P. Kinney III          
CEO & Director of Engineering 
Local Net Solutions,LLC        
770-493-8244                    
http://www.localnetsolutions.com

GPG ID: 829C6CA7 James P. Kinney III (M.S. Physics)
<jkinney at localnetsolutions.com>
Fingerprint = 3C9E 6366 54FC A3FE BA4D 0659 6190 ADC3 829C 6CA7
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