linux-kernel - Re: [PATCH 0/4] CPUFreq: Implement per policy instances of governors

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Date:	Mon, 4 Feb 2013 14:36:48 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>, cpufreq@...r.kernel.org,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	linaro-dev@...ts.linaro.org, robin.randhawa@....com,
	Steve.Bannister@....com, Liviu.Dudau@....com
Subject: Re: [PATCH 0/4] CPUFreq: Implement per policy instances of governors

On Mon, Feb 04, 2013 at 06:55:25PM +0530, Viresh Kumar wrote:
> That's not completely true. There lies cpufreq directory in cpu/cpu*/
> too, where we have per policy stuff in cpu/cpu*/, like policy tunables
> and stats. And the same is true for governor too.

$ tree /sys/devices/system/cpu/cpu0/cpufreq/
/sys/devices/system/cpu/cpu0/cpufreq/
├── affected_cpus
├── bios_limit
├── cpb
├── cpuinfo_cur_freq
├── cpuinfo_max_freq
├── cpuinfo_min_freq
├── cpuinfo_transition_latency
├── related_cpus
├── scaling_available_frequencies
├── scaling_available_governors
├── scaling_cur_freq
├── scaling_driver
├── scaling_governor
├── scaling_max_freq
├── scaling_min_freq
├── scaling_setspeed
└── stats
    ├── time_in_state
    ├── total_trans
    └── trans_table

1 directory, 19 files

$ grep -r . /sys/devices/system/cpu/cpu0/cpufreq/*
/sys/devices/system/cpu/cpu0/cpufreq/affected_cpus:0
/sys/devices/system/cpu/cpu0/cpufreq/bios_limit:4000000
/sys/devices/system/cpu/cpu0/cpufreq/cpb:1
/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq:1400000
/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq:4000000
/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq:1400000
/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_transition_latency:4000
/sys/devices/system/cpu/cpu0/cpufreq/related_cpus:0 1
/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies:4000000 3400000 2800000 2100000 1400000
/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors:powersave userspace conservative ondemand perform
/sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq:1400000
/sys/devices/system/cpu/cpu0/cpufreq/scaling_driver:acpi-cpufreq
/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor:ondemand
/sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq:4000000
/sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq:1400000
/sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed:<unsupported>
/sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state:4000000 3089328
/sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state:3400000 47448
/sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state:2800000 67185
/sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state:2100000 92731
/sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state:1400000 11416914
/sys/devices/system/cpu/cpu0/cpufreq/stats/trans_table:   From  :    To
/sys/devices/system/cpu/cpu0/cpufreq/stats/trans_table:         :   4000000   3400000   2800000   2100000   140000
/sys/devices/system/cpu/cpu0/cpufreq/stats/trans_table:  4000000:         0     34756     46388     53179    21824
/sys/devices/system/cpu/cpu0/cpufreq/stats/trans_table:  3400000:     12938         0      3755      3555     1450
/sys/devices/system/cpu/cpu0/cpufreq/stats/trans_table:  2800000:     19940         0         0      4547     2565
/sys/devices/system/cpu/cpu0/cpufreq/stats/trans_table:  2100000:     18523         0         0         0     4275
/sys/devices/system/cpu/cpu0/cpufreq/stats/trans_table:  1400000:    301168         0         0         0
/sys/devices/system/cpu/cpu0/cpufreq/stats/total_trans:799918

Show me the policy tunables here.

> That was slightly confusing to me :( The whole governor directory
> is per policy, i have to keep that in cpu/cpu*/cpufreq instead of
> cpu/cpufreq.

So make a /sys/devices/system/cpu/cpufreq/policies/ and add
functionality to assign cpus to policies or whatever the design of this
thing will be.

> Its not only for multicluster system, but a system where multiple cpus
> have separate clock control and hence multiple policy structures.

What are those systems? Examples?

> Problem with this is it would fail for single image solutions on which
> everybody is working on. So, with multiple platforms compiled into a
> single image, this wouldn't work.

Single-image solutions will enable that config option and get built with
it - no problem at all.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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