[SUPPORTO MODDING] Thread di Aiuti e Consigli alle Operazioni di modding

[alexthedrummer]

Salve a tutti. Ho appena installato la CM 10.1 e mi sono ritrovato molti nuovi governor.
Ho fatto qualche ricerca in rete per capire più o meno il funzionamento di ognuno e ci sono riuscito, tranne per uno.
Per questo governor ho trovato solo una spiegazione in inglese sul forum di XDA.
Sono abbastanza bravo in inglese, infatti ho capito qualcosina, ma non mi ha soddisfatto abbastanza, per cui, eccomi qui, a chiedere aiuto a qualche anima pia che sappia l'inglese come l'italiano e che sia interessato a leggere tutta questa spiegazione per fare un favore a me, ma anche a voi, perchè credo che l'argomento potrebbe interessarvi molto!

Grazie in anticipo a tutti, sotto riporto il testo.





Pegasusq Governor

Let's see what is pegasusq governor from Samsung which claims to be a multi core aware governor.

Some Basics to Remember Before Reading On:
Some patience is required to understand a governor.
Pegasusq is basically an ondemand based governor which also controls hotplugging.
Run Queue: We know mutiple processes can run at once on our device. These active processes are placed in an array called a run queue along with their priority values. (Priority is used by the task scheduler to determine which process is to run next) To ensure each process has a fair share of resources, each one is run for some time period then paused and placed back into the run queue. When a program is stopped to let another run - the program with the highest priority in the run queue is then allowed to execute.
Talking w.r.t to Android O.S and GS2 CPU, each core is given a run queue, which maintains both an active and expired array of processes. The scheduler selects the next process from the active array with highest priority. When a process' time period expires, it is placed into the expired array with some priority. When the active array contains no more processes, the scheduler swaps the active and expired arrays.
Wall Time is the total up time of CPU. Idle Time is the total idle time of the CPU. The difference (wall time minus idle time) gives CPU Busy Time. Load on CPU is calculated as percentage of Busy Time on Up Time. (Doesn't it make a lot of sense). Now you know exactly how is load measured.
Governor doesn't scale CPU but tells the CPU driver to do so.
Sampling means to evaluate load.
Smooth scaling is also done by CPU driver, not by governor.
Switching to pegasusq will deactivate Stand Hotplug since we don't need two logics to do the same thing at the same time and create conflicts.
Switching to a different governor from Stand hotplug will re-activate Stand Hotplug since we need a logic to control hotplugging.
Use scripts or SetCpu to change governor tunables.
Gokhanmoral modified pegasusq (originally authored by Samsung for quad core devices) in Siyah kernel to be dual core friendly.

Parameters:-

1) sampling_rate - Measured in uS and actual meaning being Sampling Interval, this factor determines how often the governor should poll for CPU usage in terms of frequency and load percentage to make scaling decisions - either scale CPU Up or scale it Down.
UNIT: Miscroseconds

2) up_threshold - Measured as percentage, when load on CPU is equal to above up threshold, CPU is scaled Up. Lower value - early scale up, and vice-verse.
UNIT: Percentage

3) sampling_down_factor - Acts as a multiplier for sampling interval for re-evaluating the load when CPU is truly busy and is on highest clock frequency (policy max). Setting to 1 makes no difference and causes CPU to immediately scale down from highest frequency. Sampling down factor is NOT valid for lower frequencies and low load conditions. Note that CPU is scaled up to max frequency when max_load_freq is greater than up_threshold*current frequency. (or to cur_freq + (freq_step * policy.max_freq) whichever is smaller) Max_load_freq is an arbitrary frequency calculated as the maximum of load_frequencies. Load_frequency is an arbitrary frequency which describes the frequency the device theoretically needs to handle 100% load, calculated as load*average_frequency.
To sum up, use non-zero sampling_down_factor to avoid governor jumping down to lower frequency even on high CPU load.
UNIT: Positive Integer

4) down_differential - After spending sampling_down_factor*sampling_rate micro seconds at maximum frequency on high load, governor samples the load again to calculate an approx target frequency to scale-down-to which should not trigger up_threshold in the next sample. (Triggering up threshold may cause jumping to max frequency again). Max_load_freq is checked against (up_threshold - down_differential) * current frequency. If found to be smaller, CPU is scaled down to a target frequency as described above. Down_differential also act as the factor to prevent aggressive scale down.
Higher value of down_differential corresponds to delayed scaling down.
UNIT: Positive Integer

5) freq_step - Defines how much as a percentage of maximum frequency, governor should increase CPU frequency each time CPU load reaches up_threshold.
UNIT: Percentage

6) cpu_up_rate - No of samples to evaluate load to scale CPU Up. After cpu_up_rate samples are finished for a frequency, CPU scale-Up logic is executed. In other words - before scaling Up, cpu_up_rate*sampling_rate micro seconds are spend at a frequency.
UNIT: Positive Integer

7) cpu_down_rate - No of samples to evaluate load to scale CPU Down. After CPU_down_rate samples are finished for a frequency, CPU scale-Down logic is executed. In other words - before scaling Down, cpu_down_rate*sampling_rate micro seconds are spend at a frequency.
UNIT: Positive Integer

8) hotplug_freq_1_1 - Up threshold frequency to turn second core On, when some other conditions is also met. ie If (minimum frequency greater than or equal to hotplug_freq 1 1 and run queue length is greater than hotplug_rq_1_1) Hotplug IN Second Core. Higher value correpsonds to delay in turning on second core.
UNIT: Kilo Hertz

9) hotplug_freq_2_0 - Down threshold frequency to turn second core Off, when some other conditions is also met. ie If (maximum frequency less than hotplug_freq 2 0 and run queue length is less than or equal to hotplug_rq_2_0) Hotplug OUT Second Core. Lower value correpsonds to delay in turning off second core.
UNIT: Kilo Hertz

10) hotplug_rq_1_1 - Threshold run queue length for second core to turn on.
UNIT: Positive Integer

11) hotplug_rq_2_0 - Threshold run queue length for second core to turn off.
UNIT: Positive Integer

12) freq_for_responsiveness - Until freq_for_responsiveness, Up Threshold considered for sampling load is up_threshold_at_min_freq. Also during the part where CPU is at maximum load frequency, governor need to find the optimal frequency as the next frequency - which should not trigger up_threshold in the next sampling. When such a frequency_next is found to be a) less than freq_for_responsiveness b) will not trigger down_threshold in the next sample, then the optimal frequency is set to freq_for_responsiveness.

13) up_threshold_at_min_freq - This threshold is used as up threshold while sampling at frequencies less than freq_for_responsiveness. Above that, normal up_threshold is used. This gives us an option to make scaling aggressive/relaxed until a frequency and normal for higher frequencies. Again, during calculation of optimal frequency which should not trigger up policy, down threshold to consider is difference between up_threshold_at_min_freq and down_differential

14) ignore_nice_load - Setting to 1 causes governor to ignore load resulted by nice processes while making scaling decisions. Nice processes are the one i/o scheduler refers to as low priority process.
UNIT: Boolean 1 or 0

15) io_is_busy - Setting to 1 causes treating i/o wait time as CPU busy time. I/O busy is just an indication that CPU is performance critical, and system is not actually idle. IO wait time is excluded from the CPU idle time value is 1.
UNIT: Boolean 1 or 0

16) max_cpu_lock - If set to zero, hotplugs in and out second core when appropriate. Otherwise specifies no of cores to be considered for hotplugging. Leave it as default 0.
UNIT: Integer 0/1/2

17) hotplug_lock - Hotplugging second core is cancelled if it's value is greater than zero. The value should be greater than value of max_cpu_lock for a non-zero value. Leave it as 0.
UNIT: Integer 0/1/2

18) *cpu_up_freq - Calculated as minimum of (its current value and maximum frequency), this tunable is actually not used by the governor.
UNIT: Kilo Hertz

19) *cpu_down_freq - Calculated as maximum of ( its current value and minimum frequency), this tunable is actually not used by the governor.
UNIT: Kilo Hertz

20) *up_nr_cpus - Calculated as minimum of (its current value and num of possible cpus), this tunable is used by the governor to indirectly make Hotplugging decisions, but may not be useful for a 2 core CPU.
UNIT: Integer 1/2

21) dvfs_debug - Set to 1 to enable governor logging. If you're an enthusiast, this may be useful to view the impact of the values for governor tunable set by inspecting the log.
UNIT: Boolean 1 or 0

* - Parameters removed in siyah kernel since they're not actually used in the governor code.

[EgYpT]

Si infatti la tizia ha fatto richiesta per la sostituzione come ho detto

[xOrion]

Leggendo online ho scoperto che questo governor è una rivisitazione del governor di default del SG3, fatto apposta per i processori multi-core (dual, quad..), adattato al processore dual core del SG2. Da quanto ho letto su internet la caratteristica principale di questo governor è il fatto che permetta ai core di lavorare con frequenze asincrone ovvero, ad esempio mentre un core gira a 920mhz l'altro, se non serve tanta potenza può girare a 350mhz o comunque a frequenze basse. Per quanto riguarda lo scalare le frequenze invece è molto simile all'ondemand. Spero di aver chiarito i tuoi dubbi

[alexthedrummer]

Leggendo online ho scoperto che questo governor è una rivisitazione del governor di default del SG3, fatto apposta per i processori multi-core (dual, quad..), adattato al processore dual core del SG2. Da quanto ho letto su internet la caratteristica principale di questo governor è il fatto che permetta ai core di lavorare con frequenze asincrone ovvero, ad esempio mentre un core gira a 920mhz l'altro, se non serve tanta potenza può girare a 350mhz o comunque a frequenze basse. Per quanto riguarda lo scalare le frequenze invece è molto simile all'ondemand. Spero di aver chiarito i tuoi dubbi

Ti ringrazio
Per caso hai scoperto anche se quando lo schermo è spento o il telefono è inattivo si spenga anche un core come accade con l'hotplug o l'intellimandX?

[xOrion]

Sinceramente non lo so, mi dispiace. Cercherò di informarmi meglio su questo dettaglio, se scopro qualcosa te lo dico

[ClaudìoS3]

Perchè non fare un thread con tutti gli altri governors?

[alexthedrummer]

Domani provvederò a farlo


Inviato dal mio U9200 con Cyanogenmod 10.1 usando Androidiani App

[ClaudìoS3]

Domani provvederò a farlo


Inviato dal mio U9200 con Cyanogenmod 10.1 usando Androidiani App

(Il messaggio è troppo corto per poter essere inviato.)

[usualemi]

Sto provando ad utilizzare questa guida con rom Vodafone b013: qualcuno l'ha fatto? A dopo x le mie impressioni

Inviato dal mio U9200 usando Androidiani App

[usualemi]

Sto provando ad utilizzare questa guida con rom Vodafone b013: qualcuno l'ha fatto? A dopo x le mie impressioni
Androidiani App

E' con molto piacere che Vi informo che la guida per sbrandizzare l'Ascend P1 funziona anche montando una rom b013!