This is a short follow-up, in case someone is interesting
how we are doing with our new configuration (two 8-proc machines with 2.7GHz Xeon MPs for database and dynamic pages
+ one dual pentium 2.8 GHz server for pound and static pages).
During the last weeks we collected some experience
from our configuration:
- number of currurrent users (with .LRN)
old system: ~500
new system: ~1000
these are actual numbers; concurrent users
denote users who performed views in a 10 minute window.
The server handles thousand users with a moderate load.
Firstly we did run into some problems, since with the
standard FC2 configuration we were not able to run
more than 400 concurrent pound
threads (stack was running out). This means that the
maximum number of concurrent transmissions was limited
to that number. We lowered the stack size per thread to
fix the problem quickly (the default values in FC2
is quite large).
- sustained rate of page views/sec
old system: 15
new system: 33
These figures are the average over one hour,
in certain seconds we had values above
200 (see the snapshot in the link below).
The number of hits is roughly 4 times this
value (including images & css-files)
- the average response time for page views is in the
range between 0.2 and 0.4 seconds (including downloads).
With that load, most processore are still more than 60%
idle. So i believe we could handle much higher load,
maybe even come close to doubling these load figures
(with os- and aol-server configuration tuning).
The difference between a fast system and a
horrendously slow system can be very little: if one
resource runs out, requests take longer and will
immediately pile up at such request rates.
These performance gains correlate highly with
the SPECint2000rate value, which seems quite
a good measure to choose configurations for
the oacs und dotlrn.
we have currently more than 500 dotlearn classes,
more than 16000 users, 5000 users visit the system
per day. We are still quite "lucky" that only
1000 use it at the same time.
The link below is a sample snapshot from live
monitoring using throttle+stats
http://media.wu-wien.ac.at/download/stat-2004-11-23a.htm
-gustaf
PS: To get a better understanding of
system bottlenecks, we are using
now hotsanic which i can certainly recommend.
It produces quite nice charts for various
system figures (memory, tcp-connections, load,
cpu usage, nr of processes, traffic, ....)
for e.g. last hour, last day,
last week, month, year. i added a quick hack
to monitor some figures from the throttle+stats
package as well (response time, view per minute,
concurrent users)
