1. Mx6ul core module use serialization - view system information (II)

The following is already in Iot-6ULX/EVB-6ULX The verification on the platform passed ,Iot-6ULX/EVB-6ULX Introduce the following ：

 

 1.Shell test

shell The test is based on shell Testing in the environment , The test process needs a series of instructions , comparison Qt test , The process will be cumbersome , But you can test the complete function .

shell Before testing , Please make sure that what is written on the development board is yocto Not in the directory test Of dtb file , Or is it Buildroot Not in the directory QT The root file system of the interface . See Chapter... For the description of software resources 2 The content in .

1.1 Check system information

1.1.1 View kernel version

Through the following two command modes , You can view the kernel version information ：

[email protected] ~# uname -a                        // View the kernel information of the current operating system

                                                  Check the kernel version information

[email protected] /# cat /proc/version                 // View the current operating system version information

                                              Check the kernel version information  

By the above instructions , You can see that the kernel version of the system is 4.14.98.

1.1.2 see CPU Information         

By the following instructions , You can see CPU Information about , Including models 、 Main frequency 、 Kernel, etc ：

[email protected] ~# cat /proc/cpuinfo              // see CPU Related information

                                                                see CPU Information  

1.1.3 see CPU Main frequency

By the following instructions , You can see CPU Supported frequency ：

[email protected] ~# 

cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies 

                                                        see CPU Current operating frequency

Operate through the above instructions , You can see CPU It supports multiple operating frequencies . That's in the multiple frequencies supported ,CPU How to choose the current working frequency , And whether the working frequency can be modified , Here we will apply it to a kernel subsystem cpufreq.

cpufreq It's a dynamic adjustment cpu Frequency module , The user can go through cpufreq Subsystem dynamically adjusts processor frequency . When the processor is running at a lower clock speed , They also consume relatively less electricity and generate less heat . This scaling of the clock speed can control the system to consume less power when it is not running at full capacity .

cpufreq The subsystem provides a total of five regulators （governors） For users to choose , They are userspace,conservative,ondemand,powersave and performance.

• performance： take CPU The frequency is fixed at the highest operating frequency it supports , Without dynamic adjustment . this It is the biggest pursuit of high performance of the system .
• powersave： take CPU frequency The fixed work is at the lowest operating frequency it supports , Without dynamic adjustment . this It is the biggest pursuit of low power consumption of the system .
• userspace： The system gives the decision-making power of frequency conversion strategy to the user mode application program , The corresponding interface is provided for the user state application program to adjust CPU  Run frequency use , It can be configured by manually editing the configuration file .
• ondemand： The on-demand variable controller will check the processor utilization , If it is found to exceed the threshold , Then the frequency will be set to the highest value available . If the governor finds that the utilization is less than the threshold , Will continue to reduce the frequency , Until it reaches the lowest value available .
• conservative： And ondemand Different ,conservative yes Adjust... Smoothly CPU frequency , The rise and fall of frequency is gradual , It will automatically adjust the upper and lower limits of frequency , and ondemand The difference is that it allocates frequencies on demand , Instead of pursuing the highest frequency .

In the use of cpufreq Before subsystem , First check cpufreq Enabled or not , By the following instructions , see cpufreq Open or not ：

[email protected] ~#/sys/devices/system/cpu/cpu0/cpufreq/ 

                                                  see cpufreq Enabled or not

As you can see from the diagram ,cpufreq Directory exists , Indicates that the system has been enabled cpufreq. By the following instructions , see cpufreq Available governors ：

[email protected] ~# 

cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors

Check the available governors

By the following instructions , see cpufreq Current governor mode ：

[email protected] ~# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor  

                                                              View the current governor  

By the following instructions , modify cpufreq Current governor mode , Here we use powersave For example , After modification, check whether the governor mode is modified successfully ：

[email protected] ~# 

echo powersave> /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor 

[email protected] ~# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor  

[email protected] ~# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq

                                                              modify cpufreq Governor mode  

As can be seen from the picture ,cpufreq The governor mode of has been ondemand To modify a powersave, also CPU It has been working at the lowest operating frequency .

1.1.4 View memory usage

adopt free command , You can check the memory usage ：

[email protected] ~# free -m                       // With MB In units of , Display memory usage

                                                                View memory usage

About free Command output content , The following is a brief introduction ：

• Mem That's ok （ The second line ） Information is about memory usage from the perspective of the operating system
• -/+ buffers/cache That's ok （ The third line ） Information is the use of system memory from the perspective of applications
• Swap That's ok （ In the fourth row ） Information is the use of exchange space
• total： Total memory
• used： The amount of memory used
• free： The amount of free memory
• shared： It has been abandoned
• buffers： Number of buffer memory
• cached： Number of cache memory

You can see from the output information of the terminal , The second and third lines of used Memory count +free The number of memory is equal to Mem Yes Total Memory count .

The specification of the development board memory chip in this test is 256MB, adopt free The total memory queried by the command is 241MB. This is because the system starts from power on to boot completion ,firmware/BIOS To keep some memory ,kernel It takes up some memory , In the end, there is something left for kernel The memory at your disposal is Mem Yes Total Memory count . This value is generally fixed during system operation .

1.1.5 Check disk usage

By the following instructions , You can check the disk usage ：

[email protected] ~# df -h                         // Display disk space and usage in a readable manner

                                          On board 4GB eMMC Development board disk usage

                                    On board 256MB NAND Flash Development board disk usage

About df Command output content , The following is a brief introduction ：

• Filesystem Column （ First column ）： Represents the pathname of the device file corresponding to the file system
• Size Column （ Second column ）： Represents the size of the partition
• Used Column （ The third column ）： Indicates used capacity
• Avail Column （ The fourth column ）： Indicates available capacity
• Use% Column （ The fifth column ）： Represents the percentage of space used by ordinary users
• Mounted on Column （ The sixth column ）： Indicates the mount point of the file system

1.1.6 see FLASH Memory capacity

/proc/partitions The file contains the partition information of the storage , Check the partition information to understand the on-board memory capacity ：

[email protected] ~# cat /proc/partitions                  // View partition information

                                              On board 4GB eMMC Development board memory capacity

mmcblk The beginning belongs to eMMC The memory of blocks The number of ,eMMC Every block The size is 512Bytes, Take all of them blocks Add it up to calculate the capacity .

                                      On board 256MB NAND Flash Development board disk usage

mtdblock The beginning belongs to NAND Flash The memory of blocks The number of ,NAND Flash Every block The size is 1024Bytes, Take all of them blocks Add it up to calculate the capacity .