Loss of performance on backup power

by

I tested my system on backup and saw considerable degradation in performance when running on backup. Here are the results:

Config:

  1. CPU: 2.0 Ghz, 6 Core, 12 Threads
  2. RAM: 16 GB
  3. UPS: 600W/ 1000VA
  4. PSU: 460W Gold Efficiency
  5. OS: Ubuntu 12.04.3
  6. Software: sysbench

*) Main Power On

andra@Ajax-Alpha:~$ sysbench --test=cpu --cpu-max-prime=100000 --num-threads=12 run
sysbench 0.4.12:  multi-threaded system evaluation benchmark

Running the test with following options:
Number of threads: 12

Doing CPU performance benchmark

Threads started!
Done.

Maximum prime number checked in CPU test: 100000


Test execution summary:
    total time:                          32.4046s
    total number of events:              10000
    total time taken by event execution: 388.4964
    per-request statistics:
         min:                                 33.81ms
         avg:                                 38.85ms
         max:                                 50.79ms
         approx.  95 percentile:              38.88ms

Threads fairness:
    events (avg/stddev):           833.3333/1.18
    execution time (avg/stddev):   32.3747/0.01

*) Main Power Off

andra@Ajax-Alpha:~$ sysbench --test=cpu --cpu-max-prime=100000 --num-threads=12 run
sysbench 0.4.12:  multi-threaded system evaluation benchmark

Running the test with following options:
Number of threads: 12

Doing CPU performance benchmark

Threads started!
Done.

Maximum prime number checked in CPU test: 100000


Test execution summary:
    total time:                          40.6918s
    total number of events:              10000
    total time taken by event execution: 487.9980
    per-request statistics:
         min:                                 34.56ms
         avg:                                 48.80ms
         max:                                730.18ms
         approx.  95 percentile:              44.61ms

Threads fairness:
    events (avg/stddev):           833.3333/0.47
    execution time (avg/stddev):   40.6665/0.01

This means the same amount of computation takes 8 extra seconds which is 25% of the time needed when running the server on main power.

I want to know if this is related to less than required backup power available to the server ? or

No matter how much backup power is provided to the server the performance will considerably degrade when running on backup ?

Answer

On Windows, the OS is capable of detecting when a server is on battery power and throttles the CPU in an effort to conserve power. I wouldn’t be surprised if you have something similar configured on your system.

Attribution
Source : Link , Question Author : i01000001 , Answer Author : MDMarra

Leave a Comment