[ltp] some power saving on thinkpad

[Alexey Fisher]

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here are patches you need http://www.linuxpowertop.org/known.php#kernel

it tested two kernels one is 2.6.21 with this patch:
http://www.linuxpowertop.org/patches/kernel-2.6.21.patch

wich make some ticks slower:
- ------------------>8----------------------
- -int dirty_writeback_interval = 5 * HZ;
+int dirty_writeback_interval = 15 * HZ;
- -------------------->8--------------------

and with CONFIG_NO_HZ=y ( tickless system )
CONFIG_HPET_TIMER is enabled but do not have any sense because my bios
not support it.

second configuration 2.6.22-rc1-mm1 with this patch:
http://www.linuxpowertop.org/patches/hpet_patches_45.patch
it enable hpet for me.

with both of them i use powersave governor.


> I get with PIT in 2.6.20 readings that are more like what you show in your
> HPET tests... weird.
> 
> But there is heavy suspicion that dynamic tics and tickless have detrimental
> effects (right now - it is a bug to be fixed) on power conservation, as they
> are indeed not helping the kernel go from C2 to C3 or C4.
> 
> Where is the HPET patch?  I could try to play with it and see if I get some
> measurements as well...
> 
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