Hyper mode for powerd

Tue Jul 9 18:40:14 UTC 2013

On Tue, 9 Jul 2013, Ian Smith wrote:

> On Sat, 6 Jul 2013 20:09:46 -0600, Warren Block wrote:
> > On Sun, 7 Jul 2013, Ian Smith wrote:
> >
> > > So even if cpu_running_mark were 100% (-r100), anything busier than 25%
> > > of our example 75MHz would shift to maximum freq immediately, where the
> > > load will likely plummet to just a few percent, way less than the 25%
> > > (at -r100) needed to keep it at that freq; ie it will most likely hunt.
> >
> > It may do that, but if so it's doing it more quickly than is visible running
> > powerd -a hyper -n hyper -v.
>
> Apart from some possible under-the-hood adjustment by thermal control in
> an over-temperature situation (?) and /etc/rc.d/power_profile poking the
> freq on AC/battery changes (not applicable to yours), as far as I know
> the only thing that adjusts freqs is powerd itself.  So no, it's not
> hunting for you.  But then, due to you having disabled p4tcc and
> acpi_throttle, your lowest speed is 1600, only 1/2.25 x 3600, a far cry
> from the up to 32:1 sort of ranges seen with p4tcc etc enabled.
>
> What I'm concerned about is what happens engaging your hyper mode with
> out-of-the-box settings, ie with p4tcc or acpi_throttle enabled as by
> default.  Would you care to find out? :)  I have no means to do so.

> > /boot/loader.conf:
> > hint.p4tcc.0.disabled="1"
> > hint.acpi_throttle.0.disabled="1"
> > hw.acpi.cpu.cx_lowest="C3"

Commenting those entries out gives:

dev.cpu.0.freq_levels: 3601/300000 3600/300000 3500/300000 3400/300000 
3300/300000 3200/300000 3100/300000 3000/300000 2900/300000 2800/300000 
2700/300000 2600/300000 2500/300000 2400/247000 2300/224000 2200/202000 
2100/182000 2000/163000 1750/142625 1600/91000 1400/79625 1200/68250 
1000/56875 800/45500 600/34125 400/22750 200/11375
dev.est.0.freq_settings: 3601/300000 3600/300000 3500/300000 3400/300000 
3300/300000 3200/300000 3100/300000 3000/300000 2900/300000 2800/300000 
2700/300000 2600/300000 2500/300000 2400/247000 2300/224000 2200/202000 
2100/182000 2000/163000 1600/91000
dev.p4tcc.0.freq_settings: 10000/-1 8750/-1 7500/-1 6250/-1 5000/-1 
3750/-1 2500/-1 1250/-1

With only that change and powerd running in hyper mode, it subjectively 
feels slower to start things.

> > I've routinely used the first two since first reading about them, I think in
> > another post by Kevin.
>
> Indeed, Kevin's been chewing on this bone for quite some time :) but I
> don't know if there's any PR + simple patch that may attract attention?
> I also don't know if the situation is the same on AMD CPUs, or others.
>
> > /etc/rc.conf:
> > powerd_flags="-a hyper -n hyper"
>
> Still on 9.1 at least,
> #define DEFAULT_ACTIVE_PERCENT	75
> #define DEFAULT_IDLE_PERCENT	50
> #define DEFAULT_POLL_INTERVAL	250	/* Poll interval in milliseconds */
>
> So hyper mode will select max freq if load at 1600MHz is > 75/4 = 18.75%
> after 250mS.  I use 200mS and there's no impact on powerd CPU usage even
> at my idle 733MHz; your responsiveness may benefit from using say 100mS?

Interesting point.  100mS is a perceptible lag.

It occurs to me that CPU load is really a poor predictor of what is 
happening on an interactive session.  powerd ought to have a wakeup 
signal.  On a keypress or mouse move or some other type of user input, 
powerd would jump to the highest frequency of the current profile.  It 
does not matter as much how it decides to drop back down.

Using devd to switch powerd profiles would be interesting.  powerd would 
have to be able to switch profiles while running, I think.  Maybe 
startup cost is not that high.

> > This is an i5, with the "3601" being turbo mode.
>
> With that beast I'm amazed you can really notice slower responsiveness
> w/ 4 CPUs @ 1600MHz, but then I get by with a P3-M at 1133/733MHz :)

Some would say I'm more particular about it than most people.  I just 
say I want it faster. :)

> It would be interesting to see cpu.0.freq_levels, est.0.freq_settings
> and the p4tcc.0 settings - and whether it hunts - with default tuning on
> some sort of lightish load - perhaps a big find like on the daily runs?

Timing 'periodic daily' now with a full cache and powerd not running:
995.53 real        28.15 user       132.17 sys

With 'powerd -a hyper -n hyper -v > /tmp/powerd.log':
2322.06 real        58.72 user       305.22 sys

Load varied enough that it would drop to 200MHz quite often.  Picking a 
random part of the log:

load   0%, current freq  200 MHz (26), wanted freq  200 MHz
load   0%, current freq  200 MHz (26), wanted freq  200 MHz
load   0%, current freq  200 MHz (26), wanted freq  200 MHz
load  11%, current freq  200 MHz (26), wanted freq  200 MHz
load   0%, current freq  200 MHz (26), wanted freq  200 MHz
load   0%, current freq  200 MHz (26), wanted freq  200 MHz
load  10%, current freq  200 MHz (26), wanted freq  200 MHz
load   4%, current freq  200 MHz (26), wanted freq  200 MHz
now operating on AC power; changing frequency to 3601 MHz
load  55%, current freq  200 MHz (26), wanted freq 3601 MHz
changing clock speed from 200 MHz to 3601 MHz
now operating on AC power; changing frequency to 200 MHz
load   4%, current freq 3601 MHz ( 0), wanted freq  200 MHz
changing clock speed from 3601 MHz to 200 MHz
load   4%, current freq  200 MHz (26), wanted freq  200 MHz
now operating on AC power; changing frequency to 3601 MHz
load  20%, current freq  200 MHz (26), wanted freq 3601 MHz
changing clock speed from 200 MHz to 3601 MHz
now operating on AC power; changing frequency to 200 MHz
load   3%, current freq 3601 MHz ( 0), wanted freq  200 MHz
changing clock speed from 3601 MHz to 200 MHz
load   4%, current freq  200 MHz (26), wanted freq  200 MHz
now operating on AC power; changing frequency to 3601 MHz
load  21%, current freq  200 MHz (26), wanted freq 3601 MHz
changing clock speed from 200 MHz to 3601 MHz
now operating on AC power; changing frequency to 200 MHz
load   0%, current freq 3601 MHz ( 0), wanted freq  200 MHz