On 1/27/21 8:02 AM, Len Ovens wrote:
> On Wed, 27 Jan 2021, Michael Jarosch wrote:
>
>> As soon as frequency switching was introduced we LAU were told, not
>> to use it to save xruns. And as far as I can tell, the rule still
>> valid. Is there a chance in the future that we can stop thinking
>> about it, because it just won't matter? Are we forced blowing loads
>> of energy or do we spent too much time in sluggish UEFI menus?
>
> It depends. Setting jack to frame size 64 or lower has in my
> experience shown xruns with frequency switching. This includes Intel's
> "Boost" setting which is not turned off by setting performance. There
> seems to be no problem when the speed goes up but I often see an xrun
> when the speed goes down (just at speed change).
>
> However, Intel has been doing speed switching in the CPU for a while
> now and we are still able to set a steady speed with that on the fly.
> So with the AMD it may be similar. It may still be possible to set an
> upper and lower speed limit. What they do not say, is that the
> advertized speed may not be usable in steady state. With the Intel,
> the advertized speed can be set for all cores and run that way at 100%
> core use and run forever without over heating. AMD tends to advertize
> a cpu speed based on some cores running slower and the cpu managing
> heat by slowing some cores down. In this case one will have to
> experiment to find out what speed can be safely run on all cores
> without over heating and use that speed for audio. Hopefully this can
> be set on the fly.
>
Intel doesn't run at top speed "forever". Fastest clock I've got from my
nominal 5GHz-max i9 in my Dell XPS 15 is 4.7GHz. Intel runs clock speed
until thermals say "Slow down." If you're talking about a laptop, the
specific laptop's ability to dissipate heat is the controlling factor.
I'm not sure that Intel thermal control is anywhere within reach of BIOS
and OS software.
> Another comment of "blowing loads of energy" with performance mode. It
> was actually found that the old "ondemand" governor actually used more
> power than "performance" in many cases. Ondemand has to wake up every
> once in a while to see what is happening, but in performance mode the
> core can go to an idle state. The newer intel powersave mode does not
> have this problem but AMD (although they started work on their own
> governor for linux) can only use ondemand.
>
> The easiest way to see power use is to watch core temperature... all
> power used ends up as heat.
It and clock are good indicators.
-- David W. Jones gnome@hawaii.rr.com authenticity, honesty, community http://dancingtreefrog.com "My password is the last 8 digits of π." _______________________________________________ Linux-audio-user mailing list Linux-audio-user@lists.linuxaudio.org https://lists.linuxaudio.org/listinfo/linux-audio-userReceived on Fri Jan 29 04:15:02 2021
This archive was generated by hypermail 2.1.8 : Fri Jan 29 2021 - 04:15:02 EET