Why won't this have an effect on a single dual-core cpu? This option
makes the scheduler use one core for all tasks as long as load on this
single core won't get too high - so there should be an impact on power
usage because the second core will be a lot more idle and stay in
C-states longer and eventually run at a lower frequency.
I don't know about AMDs Opterons or X2 CPUs, but the Intel Core2 Duo can
put the cores into sleep states individually and even make the cores run
at different speeds - at least I heard that and even saw it on my new
system.
So why won't sched_mc_power_savings affect systems with only one
dual-core cpu?
Peter
Arjan van de Ven wrote:
Martin Milata wrote:
Hi,
what exactly is the effect of enabling "power save mode" on multi-core
aware CPU scheduler?
( echo 1 > /sys/devices/system/cpu/sched_mc_power_savings )
As far as I understood from [1], it only affects systems with more
than one multi-core physical CPU. Does it have any effect on a system
with one dual-core CPU?
nope.
And in theory (!) powertop will only suggest it for multi-physical
cpus.. in practice there seems to be a bug in the detection for this ;)
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