>> 2) you're free to carry your own tuned profile for your
product
> The patch adds balanced-hpc profile. Do we need another profile? Couldn't
> we just
> lower the sampling rate in the original balanced profile (e.g.
> conditionally if
> the knob exists). Would it negatively affect the latency so much to justify
> new
> profile? Does anybody have any figures? Well, in RHEL we mostly use
> performance or
> low latency profiles or derivatives, so it probably shouldn't pose much
> problem
> there.
We could add to the original balanced profile. Ideally, It shouldn't affect
the latency, rather
it should help as it would hold the processors at higher frequency for a
longer time.
But as the sampling rate is reduced, the system power would drop slowly,
after it reaches
max frequency. So machines running in energy-constrained environment (like
battery powered)
or platforms who care about power more than performance, would not like it.
So i feel a new
profile would be a good idea.
I like things to be simple :) So if there is more benefit than loss I would
vote for inclusion into the original balanced profile.
For decision how to handle it it would be beneficial to have figures, especially
figures regarding the power consumption. If it is not time critical I think we
could measure something during next month - there will be new person joining
the project :) Or if it happened that there is anybody who already measured it,
please share the results.
> Personally I would rewrite the patch a bit to learn Tuned about
the knob
> and
> not use the script, but this is minor.
I agree, i will rewrite the patch which could be set easily through
tuned.conf without the script.
I was thinking of adding "od_sampling_down_factor" as a config_options in
plugin_cpu.py.
Is this the right place to added? Any other suggestions ?
Yes, plugin_cpu is the right place. I see the option beneficial. I think we could
start with Tuned support for the knob and decide later whether to introduce new
profile or not. The name for the option could be also:
"ondemand_sampling_down_factor" or simply "sampling_down_factor" in
case you think
it may be beneficial for other governors as well (e.g. in case such knob appears
later so it could be handled easily in the Tuned code without introducing new option)
thanks & regards
Jaroslav