SIGs/PowerManagement/RHEL5xF12comparison

RHEL 5 x Fedora 12
This is the first power consumption comparison of RHEL 5 and Fedora 12. The results was measured by BLTK that gets power consumption data from laptop's battery info. There were used three workloads for this comparison:
 * Idle - simulates no interaction from user side (no screen saver defined)
 * Office - simulates working in Open Office with breaks
 * Reader - simulates reading text in Firefox

Used Hardware and OS
Laptop

LENOVO ThinkPad T61 * CPU Intel Core2 Duo CPU T7500 2.20 GHz * Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller * LCD 15" 1680x1050x24 * Memory 2 GB * HDD 100 GB * Battery designed and usable capacity 56.16 Wh

RHEL 5

Kernel release 2.6.18-164.el5

Fedora 12

Kernel release 2.6.31-33.fc12.x86_64

Test description
The tests were done on laptop installed with RHEL 5, Fedora 11 and Fedora 12 using shared /home. The workload mentioned above was used with following specification:

Idle test - test was running for 10 minutes

bltk -I -T 600

Office test - Open Office workload was running with three repetitions (work simulation repeated 3x)

bltk -O -n 3

Reader test - Each of tests was running also with three repetitions. Firefox is a reader application by default (bltk.conf).

bltk -R -n 3

Idle workload
RHEL 5

F12

F12 tuned



Office workload
RHEL 5

Fedora 12

Fedora 12 tuned



Reader workload
RHEL 5

Fedora 12

Fedora 12 tuned



Conclusion

 * 1) Fedora 12 is more power saving against RHEL 5 but it's not valid in all cases. The results illuminate dependency of power saving on used application. This conclusion will be investigated deeper in the future (e.g. test using another browser).
 * 2) The next finding shows dependency of power consumption on charging rate. The charts attached to particular work loads display growing power drain during battery discharging. There is currently no clear explanation for this effect. There is probably influence of two process - growing amperage that compensates falling voltage during discharging battery and growing hardware temperature (thermal absorption of hardware components and growing amperage).
 * 3) The data of CPU displays different ways in using two cores CPUs.
 * 4) Tuned is able to increase power saving but not in all cases.