Kprofiles

Table of Contents

1. About
2. Supported Kernel Version
3. Usage
4. Available APIs
5. How To Contribute
6. License
7. Our Team

About

Kprofiles is a simple Linux kernel module that can be used to regulate in-kernel activities such as boosts that are normally not exposed to the userspace. Kprofiles operates in a profile-oriented manner So, It has four profile modes: Disabled, Battery, Balanced, and Performance. Each mode is allocated a mode number. Developers can use the Kprofiles API function in conditions to limit or enable in-kernel tasks in a certain profile mode (look at usage section for example). Userspace can interact with Kprofiles by adjusting the mode number in /sys/module/kprofiles/parameters/kp_mode. The table below shows which mode number corresponds to the profile mode.

Profile Mode	Mode Number
Disabled (default)	0
Battery	1
Balanced	2
Performance	3

Furthermore, Kprofiles provides automatic profile changer (auto Kprofiles), which uses FB notifier or MSM DRM notifier to enforce battery profile mode when the device's screen goes off and switches back to previously active mode when the device wakes up. Users can disable or enable this feature at runtime without recompiling the kernel by changing the bool value in /sys/module/kprofiles/parameters/auto_kprofiles

Kprofiles additionally has API functions for switching profiles in response to any in-kernel event. For further information, please see the table of Available APIs

Supported Kernel Versions

Kprofiles is tested on Linux 3.10+ kernels

Using kprofiles in your Linux kernel source

If you're using git, using git subtree or git submodule is highly recommended.

1. Add this repository to drivers/misc/kprofiles

2. Modify drivers/misc/Kconfig

menu "Misc devices"

source "drivers/misc/genwqe/Kconfig"
+source "drivers/misc/kprofiles/Kconfig"
source "drivers/misc/echo/Kconfig"
endmenu

3. Modify =drivers/misc/Makefile=

obj-$(CONFIG_GENWQE)     += genwqe/
+obj-$(CONFIG_KPROFILES) += kprofiles
obj-$(CONFIG_ECHO)       += echo/

4. Define the api function you need in the required file using extern, kprofiles can be used in various places like for example boosting drivers, below is an example of using kprofiles in kernel/fork.c to control cpu and ddr boosts during zygote forking using kp_active_mode() API.

+ extern int kp_active_mode(void);
/*
 *  Ok, this is the main fork-routine.
 *
 * It copies the process, and if successful kick-starts
 * it and waits for it to finish using the VM if required.
 */
long _do_fork(unsigned long clone_flags,
          unsigned long stack_start,
          unsigned long stack_size,
          int __user *parent_tidptr,
          int __user *child_tidptr,
          unsigned long tls)
{
    struct task_struct *p;
    int trace = 0;
    long nr;

    /* Boost CPU to the max for 50 ms when userspace launches an app */
    if (task_is_zygote(current)) {
-       cpu_input_boost_kick_max(50);
-       devfreq_boost_kick_max(DEVFREQ_MSM_LLCCBW, 50);
-       devfreq_boost_kick_max(DEVFREQ_MSM_CPUBW, 50);
+   /*
+    * Dont boost CPU & DDR if battery saver profile is enabled
+    * and boost CPU & DDR for 25ms if balanced profile is enabled
+    */
+       if (kp_active_mode() == 3 || kp_active_mode() == 0) {
+           cpu_input_boost_kick_max(50);
+           devfreq_boost_kick_max(DEVFREQ_MSM_LLCCBW, 50);
+           devfreq_boost_kick_max(DEVFREQ_MSM_CPUBW, 50);
+       } else if (kp_active_mode() == 2) {
+           cpu_input_boost_kick_max(25);
+           devfreq_boost_kick_max(DEVFREQ_MSM_LLCCBW, 25);
+           devfreq_boost_kick_max(DEVFREQ_MSM_CPUBW, 25);
+       } else {
+           pr_info("Battery Profile Active, Skipping Boost...\n");
+       }
    }

and you are good to go!

Available APIs

API Function Name	Info	Arguments required
kp_active_mode()	This API function returns a number from 0 and 3 depending on the profile selected. It can be used in conditions to regulate boosts and other things.	None
kp_set_mode(unsigned int level)	This api function can be used to change profile to any given mode during any in-kernel event.	level :- the mode number.
kp_set_mode_rollback(unsigned int level, unsigned int duration_ms)	This api function can be used to change profile to any given mode for a specific period of time during any in-kernel event, then return to the previously active mode.	level :- the mode number. duration_ms :- the amount of time (in milliseconds) the specified mode should be active before switching back to the previously used mode.

How To Contribute

You can contribute to Kprofiles by sending us pull requests with the changes, Please provide a precise message with the commit explaining why you're making the change.

License

This project is licensed under GPL-2.0.

Team

• Dakkshesh : kernel module Author/Maintainer
• Cyberknight777 : kernel module Co-Maintainer | Kprofiles Manager Maintainer
• Vyom Desai : Kprofiles Manager (rom package) Author/Maintainer
• Martin Valba : Kprofiles Manager (standalone app) Author/Maintainer
• Someone5678 : Kprofiles Manager (rom package) Co-Maintainer