|
CERN openlab II - Platform CC - Optimization
Thermal Testing
The CERN computing center has a limitiation for electric
power of 2.5MW. Given this hard limit, we are naturally
interested in getting the most compute power out of this
electric power.
To be useful the thermal testing of a server has to go hand
in hand with testing the performance of this server. One of
the main metric by which a servers capabilities can be
judged is "performance per Watt" which is "SPECint2000/Watt"
in our case.
But the project goes beyond just measuring power consumption
under load. We also try to better understand where in a
server the power is consumed. The CPUs have been the main
power consumer for a long time now, but with the new
generation of very power efficient CPUs, the power
consumption of the main memory comes into focus now.
Some of the power measurements results so far:
-
FB-DIMM (memory in Woodcrest servers): ~10W per GByte
under full load
-
with 2GB per core this means 80W for the memory alone in
a Woodcrest
-
hard disks: ~10W idle and ~15W under load (of course,
only the models we tested, other models may have
different power consumptions)
As for SPECint2000/Watt measured with CERN settings the
results look as follows:
(the results are only meaningful for a specific system
(type) in connection with the used compiler, and possibly
additional libraries!)
Those numbers depend on a lot
of factors. Most prominently the used compiler.
If the Intel compiler is used with the highest optimization,
the performance is much better: ~30 SPECint2000/Watt. | 
