Hyper mode for powerd

[Ian Smith]

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.

 > > You don't appear to be taking any notice of the -i idle percentage here;
 > > perhaps that would be a more useful shift-down criterion?  Even so, with
 > > a full house of frequencies, I can't see this being easy to tune as is.
 > > 
 > > Show "sysctl -a | egrep 'freq|cx'" and we'll have something to chew on?
 > > And your powerd_flags setting?
 > 
 > /boot/loader.conf:
 > hint.p4tcc.0.disabled="1"
 > hint.acpi_throttle.0.disabled="1"
 > hw.acpi.cpu.cx_lowest="C3"
 > 
 > 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?

 > performance_cx_lowest="Cmax"
 > performance_cpu_freq="HIGH"
 > 
 > That grep provides a lot of unrelated "freq" stuff, so here's a guess at what
 > you want to see:

Yes, I tried it on a borrowed Lenovo SL500; lots more than on my T23!

 > hw.acpi.cpu.cx_lowest: C8

Never heard of C8, but I'm way out of touch with latest hardware.

 > machdep.acpi_timer_freq: 3579545
 > machdep.i8254_freq: 1193182
 > machdep.tsc_freq: 3309792585
 > dev.cpu.0.freq: 3601
 > 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 1600/91000

Interesting specifying 300W right down to 2500MHz before decreasing, and 
it's quite a large set of primary freqs, only 4 on one 2400MHz Core2Duo.

 > dev.cpu.0.cx_supported: C1/1/1 C2/2/64 C3/3/96
 > dev.cpu.0.cx_lowest: C8
 > dev.cpu.0.cx_usage: 31.99% 64.88% 3.12% last 1203us

Some changes in -current there.  cpu.1.* to cpu.3.* the same as usual, 
apart from varying cx_usage, so you can safely omit them from reports.

[..]

 > 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

[.. same as freq_levels, without throttling ..]

 > 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 :)

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?

cheers, Ian