powerd / cpufreq question
Alexander Motin
mav at FreeBSD.org
Sat Apr 9 15:29:28 UTC 2011
On 09.04.2011 17:39, Bartosz Fabianowski wrote:
> I just noticed this thread a day after my own fight with powerd and load
> percentages that did not seem to make any sense.
>
> The patch I came up with is attached. It modifies powerd to use the load
> percentage of the busiest core. This reduces the range of values back to
> 0%...100% also for multi-core systems.
While using maximum of loads can be better then using levels above 100%,
it won't properly handle cases of dependent or frequently migrating
threads, that are handled now with summary load and levels less then
100%. While existing powerd algorithm is indeed not perfect, it is the
only relatively performance-safe, unlike others propositions.
I won't argue about adding more algorithms/options to powerd, optimized
for handling different situations, but I believe that default should
remain safe.
> On my Core i7 setup here, the change seems to work well.
... in your specific workload. And you haven't described how you
measured system performance to prove that it haven't decreased.
--
Alexander Motin
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