We currently do not allow the user to select a power/performance profile.
This seems like something we eventually require for tunablity.

The initial OpenSolaris could not introduce any performance regressions
over a wide range of benchmarks.  There is a huge opportunity for
tuning for power if we are not constrained by 100% performance.
I definitely saw during evaluation power improvements from c-state
governor changes such as Aubrey's proposal.  There are a number of
thread scheduling improvements as well I would like to get back to.  ;-)
Having power/perf profiles or "knobs" would really make it easier
to introduce better algorithms which work really well in specific
situations with different power, performance, and response time
requirements.

Regards,
Bill



On 05/22/09 16:17, Bill Holler wrote:
> Hi Aubrey,
>
> Time based sample periods were initially investigated, but they
> performed poorly with "ping pong" type workloads such as
> producer consumer etc.  The problem was it took too long to
> recognize a load change when the CPU had very short idle
> and load periods.  The current idle-rate based sampling shows
> very little to no regression on benchmarks such as libmicro.
>
> How does the proposed change look in libmicro?
>
> We may need to use a hybrid governor which looks at both
> idle rate and a fixed sample period.
>
> Thank you,
> Bill
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