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  1.    #1  
    I'm and end user, sober most of the day and do have a minor in computer science back when dos ruled (1982).

    Love the work everyone has done on UberKernel and Govnah, but after reading just about everything, I think it would be helpful to explain the setting options available in Govnah in layman's terms.
    There are so many and the bourbon has done damage to my brain.

    I was using CPUScaler and found the best setting for me was 250-800.

    I did find this on a thread to get things started. It is missing the Screenstate however. If you'd be so kind to copy and paste the below adding in simple definitions, I think it would help a lot of folks.

    Thanks!
    Ezrabrooks51

    2.1 Performance
    ---------------
    The CPUfreq governor "performance" sets the CPU statically to the highest frequency within the borders of scaling_min_freq and scaling_max_freq.

    2.2 Powersave
    -------------
    The CPUfreq governor "powersave" sets the CPU statically to the lowest frequency within the borders of scaling_min_freq and scaling_max_freq.

    2.3 Userspace
    -------------
    The CPUfreq governor "userspace" allows the user, or any userspace program running with UID "root", to set the CPU to a specific frequency by making a sysfs file "scaling_setspeed" available in the CPU-device directory.

    2.4 Ondemand
    ------------
    The CPUfreq governor "ondemand" sets the CPU depending on the current usage. To do this the CPU must have the capability to switch the frequency very quickly.

    2.5 Conservative
    ----------------
    The CPUfreq governor "conservative", much like the "ondemand" governor, sets the CPU depending on the current usage. It differs in behaviour in that it gracefully increases and decreases the CPU speed rather than jumping to max speed the moment there is any load on the CPU.
  2. #2  
    Whats the diff btw screenstate and on demand?
  3. #3  
    Quote Originally Posted by Ezrabrooks51 View Post
    There are so many and the bourbon has done damage to my brain.
    that'll happen lol
  4. #4  
    16 Clock scaling allows you to change the clock speed of the CPUs on the
    17 fly. This is a nice method to save battery power, because the lower
    18 the clock speed, the less power the CPU consumes.
    19
    20
    33
    34
    35
    36 1. What Is A CPUFreq Governor?
    37 ==============================
    38
    39 Most cpufreq drivers (in fact, all except one, longrun) or even most
    40 cpu frequency scaling algorithms only offer the CPU to be set to one
    41 frequency. In order to offer dynamic frequency scaling, the cpufreq
    42 core must be able to tell these drivers of a "target frequency". So
    43 these specific drivers will be transformed to offer a "->target"
    44 call instead of the existing "->setpolicy" call. For "longrun", all
    45 stays the same, though.
    46
    47 How to decide what frequency within the CPUfreq policy should be used?
    48 That's done using "cpufreq governors". Two are already in this patch
    49 -- they're the already existing "powersave" and "performance" which
    50 set the frequency statically to the lowest or highest frequency,
    51 respectively. At least two more such governors will be ready for
    52 addition in the near future, but likely many more as there are various
    53 different theories and models about dynamic frequency scaling
    54 around. Using such a generic interface as cpufreq offers to scaling
    55 governors, these can be tested extensively, and the best one can be
    56 selected for each specific use.
    57
    58 Basically, it's the following flow graph:
    59
    60 CPU can be set to switch independently | CPU can only be set
    61 within specific "limits" | to specific frequencies
    62
    63 "CPUfreq policy"
    64 consists of frequency limits (policy->{min,max})
    65 and CPUfreq governor to be used
    66 / \
    67 / \
    68 / the cpufreq governor decides
    69 / (dynamically or statically)
    70 / what target_freq to set within
    71 / the limits of policy->{min,max}
    72 / \
    73 / \
    74 Using the ->setpolicy call, Using the ->target call,
    75 the limits and the the frequency closest
    76 "policy" is set. to target_freq is set.
    77 It is assured that it
    78 is within policy->{min,max}
    79
    80
    81 2. Governors In the Linux Kernel
    82 ================================
    83
    84 2.1 Performance
    85 ---------------
    86
    87 The CPUfreq governor "performance" sets the CPU statically to the
    88 highest frequency within the borders of scaling_min_freq and
    89 scaling_max_freq.
    90
    91
    92 2.2 Powersave
    93 -------------
    94
    95 The CPUfreq governor "powersave" sets the CPU statically to the
    96 lowest frequency within the borders of scaling_min_freq and
    97 scaling_max_freq.
    98
    99
    100 2.3 Userspace
    101 -------------
    102
    103 The CPUfreq governor "userspace" allows the user, or any userspace
    104 program running with UID "root", to set the CPU to a specific frequency
    105 by making a sysfs file "scaling_setspeed" available in the CPU-device
    106 directory.
    107
    108
    109 2.4 Ondemand
    110 ------------
    111
    112 The CPUfreq governor "ondemand" sets the CPU depending on the
    113 current usage. To do this the CPU must have the capability to
    114 switch the frequency very quickly. There are a number of sysfs file
    115 accessible parameters:
    116
    117 sampling_rate: measured in uS (10^-6 seconds), this is how often you
    118 want the kernel to look at the CPU usage and to make decisions on
    119 what to do about the frequency. Typically this is set to values of
    120 around '10000' or more. It's default value is (cmp. with users-guide.txt):
    121 transition_latency * 1000
    122 Be aware that transition latency is in ns and sampling_rate is in us, so you
    123 get the same sysfs value by default.
    124 Sampling rate should always get adjusted considering the transition latency
    125 To set the sampling rate 750 times as high as the transition latency
    126 in the bash (as said, 1000 is default), do:
    127 echo `$(($(cat cpuinfo_transition_latency) * 750 / 1000)) \
    128 >ondemand/sampling_rate
    129
    130 show_sampling_rate_min:
    131 The sampling rate is limited by the HW transition latency:
    132 transition_latency * 100
    133 Or by kernel restrictions:
    134 If CONFIG_NO_HZ is set, the limit is 10ms fixed.
    135 If CONFIG_NO_HZ is not set or no_hz=off boot parameter is used, the
    136 limits depend on the CONFIG_HZ option:
    137 HZ=1000: min=20000us (20ms)
    138 HZ=250: min=80000us (80ms)
    139 HZ=100: min=200000us (200ms)
    140 The highest value of kernel and HW latency restrictions is shown and
    141 used as the minimum sampling rate.
    142
    143 show_sampling_rate_max: THIS INTERFACE IS DEPRECATED, DON'T USE IT.
    144
    145 up_threshold: defines what the average CPU usage between the samplings
    146 of 'sampling_rate' needs to be for the kernel to make a decision on
    147 whether it should increase the frequency. For example when it is set
    148 to its default value of '95' it means that between the checking
    149 intervals the CPU needs to be on average more than 95% in use to then
    150 decide that the CPU frequency needs to be increased.
    151
    152 ignore_nice_load: this parameter takes a value of '0' or '1'. When
    153 set to '0' (its default), all processes are counted towards the
    154 'cpu utilisation' value. When set to '1', the processes that are
    155 run with a 'nice' value will not count (and thus be ignored) in the
    156 overall usage calculation. This is useful if you are running a CPU
    157 intensive calculation on your laptop that you do not care how long it
    158 takes to complete as you can 'nice' it and prevent it from taking part
    159 in the deciding process of whether to increase your CPU frequency.
    160
    161
    162 2.5 Conservative
    163 ----------------
    164
    165 The CPUfreq governor "conservative", much like the "ondemand"
    166 governor, sets the CPU depending on the current usage. It differs in
    167 behaviour in that it gracefully increases and decreases the CPU speed
    168 rather than jumping to max speed the moment there is any load on the
    169 CPU. This behaviour more suitable in a battery powered environment.
    170 The governor is tweaked in the same manner as the "ondemand" governor
    171 through sysfs with the addition of:
    172
    173 freq_step: this describes what percentage steps the cpu freq should be
    174 increased and decreased smoothly by. By default the cpu frequency will
    175 increase in 5% chunks of your maximum cpu frequency. You can change this
    176 value to anywhere between 0 and 100 where '0' will effectively lock your
    177 CPU at a speed regardless of its load whilst '100' will, in theory, make
    178 it behave identically to the "ondemand" governor.
    179
    180 down_threshold: same as the 'up_threshold' found for the "ondemand"
    181 governor but for the opposite direction. For example when set to its
    182 default value of '20' it means that if the CPU usage needs to be below
    183 20% between samples to have the frequency decreased.
    184
    185 3. The Governor Interface in the CPUfreq Core
    186 =============================================
    187
    188 A new governor must register itself with the CPUfreq core using
    189 "cpufreq_register_governor". The struct cpufreq_governor, which has to
    190 be passed to that function, must contain the following values:
    191
    192 governor->name - A unique name for this governor
    193 governor->governor - The governor callback function
    194 governor->owner - .THIS_MODULE for the governor module (if
    195 appropriate)
    196
    197 The governor->governor callback is called with the current (or to-be-set)
    198 cpufreq_policy struct for that CPU, and an unsigned int event. The
    199 following events are currently defined:
    200
    201 CPUFREQ_GOV_START: This governor shall start its duty for the CPU
    202 policy->cpu
    203 CPUFREQ_GOV_STOP: This governor shall end its duty for the CPU
    204 policy->cpu
    205 CPUFREQ_GOV_LIMITS: The limits for CPU policy->cpu have changed to
    206 policy->min and policy->max.
    207
    208 If you need other "events" externally of your driver, _only_ use the
    209 cpufreq_governor_l(unsigned int cpu, unsigned int event) call to the
    210 CPUfreq core to ensure proper locking.
    211
    212
    213 The CPUfreq governor may call the CPU processor driver using one of
    214 these two functions:
    215
    216 int cpufreq_driver_target(struct cpufreq_policy *policy,
    217 unsigned int target_freq,
    218 unsigned int relation);
    219
    220 int __cpufreq_driver_target(struct cpufreq_policy *policy,
    221 unsigned int target_freq,
    222 unsigned int relation);
    223
    224 target_freq must be within policy->min and policy->max, of course.
    225 What's the difference between these two functions? When your governor
    226 still is in a direct code path of a call to governor->governor, the
    227 per-CPU cpufreq lock is still held in the cpufreq core, and there's
    228 no need to lock it again (in fact, this would cause a deadlock). So
    229 use __cpufreq_driver_target only in these cases. In all other cases
    230 (for example, when there's a "daemonized" function that wakes up
    231 every second), use cpufreq_driver_target to lock the cpufreq per-CPU
    232 lock before the command is passed to the cpufreq processor driver.
    "Patience, use the force, think." Obi-Wan


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  5. Kedar's Avatar
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    #5  
    Yeah I was a little confused yesterday installing both.

    I was an alpha tester and found that installing the 720 and 800 .sh files was easier than this.
    Then I sorta' figured it all out.
    I'm using screenstate 500-800 until they get it to go lower, so I can do 250-800.
  6. #6  
    Quote Originally Posted by Kedar View Post
    ...I'm using screenstate 500-800 until they get it to go lower, so I can do 250-800.
    Same here, though I'm maxing it at 720. Noticeable difference in temp w/no noticeable difference in performance.
    -Joshua
    I've decided to become enigmatic.
  7. #7  
    Quote Originally Posted by Kedar View Post
    Yeah I was a little confused yesterday installing both.

    I was an alpha tester and found that installing the 720 and 800 .sh files was easier than this.
    Then I sorta' figured it all out.
    I'm using screenstate 500-800 until they get it to go lower, so I can do 250-800.
    Marco has released an alpha kernel that DOES go lower. it will actualy drop to 125when screen is off if you want it to. check it out.....
    http://forums.precentral.net/web-os-...erimental.html
  8. #8  
    Quote Originally Posted by jayjam99 View Post
    Marco has released an alpha kernel that DOES go lower. it will actualy drop to 125when screen is off if you want it to. check it out.....
    http://forums.precentral.net/web-os-...erimental.html
    Yep, I'm aware of it. I have a rule to not install packages not in repo - I suck at remembering to check for updates, etc.
    -Joshua
    I've decided to become enigmatic.
  9. #9  
    None of this has cleared it up for me. If I select the "userspace" setting and select 250 min, 720 max, and 600 setspeed, what will cause the CPU to change from 600? Everytime I go into Govnah to see what is going on, it seems locked at 600 (unless I've just restarted, in which case it's at 500). Are "conservative" and "ondemand" the only two settings that dynamically change?
  10. #10  
    I'm confused too. Installed this yesterday after using the 800mhz patch for a while. It was working fine, set at screenstate. But now it seems to be stuck at 800mhz in screenstate. The other governors will drop the CPU speed down, but screenstate seems stuck at 800. Any ideas?

    I'm not really sure which one of these governors I should be using. I want fast speed when using the device and good battery life. Screenstate seemed like the prescription, but....

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