Preface

In a recent project , Want statistics make The time of the whole project , To add to Makefile in , After image generation , Automatically output the time to the screen .
Research. , Discovery can be achieved in the following two ways .

One 、time Tools

The easiest way , Use time Tools to count the running time of scripts , Baidu Encyclopedia right time Explanation of the order :

time Commands are often used to measure the running time of a command 

The test environment is ubuntu20.04, Input... At the terminal time command

time
real    0m0.000s
user    0m0.000s
sys     0m0.000s

• real : The whole execution process takes time , Unit second
• user: Time spent running programs in user space , Unit second
• sys: Time spent running programs in kernel space , Unit second

With one drive demo Take the compilation process as an example .

In the compile Directory , function Makefile Of make action .

make

make -C /lib/modules/`uname -r`/build M=/home/xxx/Desktop/xxx/test/driver modules
make[1]: Entering directory '/usr/src/linux-headers-5.13.0-41-generic'
  CC [M]  /home/xxx/Desktop/xxx/test/driver/msg_test.o
  MODPOST /home/xxx/Desktop/xxx/test/driver/Module.symvers
  CC [M]  /home/xxx/Desktop/xxx/test/driver/msg_test.mod.o
  LD [M]  /home/xxx/Desktop/xxx/test/driver/msg_test.ko
  BTF [M] /home/xxx/Desktop/xxx/test/driver/msg_test.ko
Skipping BTF generation for /home//home/xxx/Desktop/xxx/test/driver/msg_test.ko due to unavailability of vmlinux
make[1]: Leaving directory '/usr/src/linux-headers-5.13.0-41-generic'

real    0m14.638s
user    0m0.663s
sys     0m0.560s

You can see the whole process , Time consuming 14.638 second , The time consumed in user mode and kernel mode are 0.663 second 、0.560 second .

Two 、 To achieve

Ideas

All we need to do is Makefile Start running , Record a timestamp .Makefile Record a timestamp when the execution is completed , In the subtraction of time , You can get the total running time .

1、 Get the start timestamp .

May adopt linux Systematic /proc/uptime To get the current time .

You can analyze it first /proc/uptime What's in it , It says Linux System running time .

cat /proc/uptime

4643.14 34329.17

• First column 4643.14, It is system startup , To cat /proc/uptime Command run time , The time that the system has been running , The unit is seconds .
• Second column 34329.17, Is the system idle time , It has something to do with the system audit , At this time , Since the system was started , All cores , The sum of free time , The author's ubuntu yes 8 Check the number , This parameter doesn't care much , It has nothing to do with the content of this implementation .

2、 The idea of extracting timestamp

Only need to use awk command , adopt . Division /proc/uptime What's in it , You can get the timestamp of seconds .

cat /proc/uptime | awk -F "." '{print $1}'
4643

As long as Makefile At the end of the run , Get it again /proc/time The number of seconds inside , Subtract the values before and after , You can get the time difference , That is, the running time of the project .

3、date The command conversion timestamp is Mm / DD / yyyy HHM / S Format

Can pass data --help Order to see data Usage of .

data -d @ Time stamp  [format]

format Use the following parameters , Acquisition date 、 when 、 branch 、 second

%j   day of year (001..366)
%H   hour (00..23)
%M   minute (00..59)
%S   second (00..60)

At this time, the timestamp entered is in 1970 Started as an operation in . As obtained above 4643, As bloggers UTC-8 Time for , So time + 了 8 Hours ,4643 The corresponding is 9 spot 17 branch 23 second .

date -d @4643
1970 year  01 month  01 Japan   Thursday  09:17:23 CST

\- u Options

add -u Options , You can make time in UTC For reference , No time zone offset .

date -u [email protected]
1970 year  01 month  01 Japan   Thursday  01:17:23 UTC

You can see that the time is 1 spot 17 branch 23 second , It happens to be the running time of our system ,4643 second .

Format the interception time, minutes and seconds

date -u -d @4643 +%Hh:%Mm:%Ss
01h:17m:23s

+%Hh:%Mm:%Ss In the command %H、%M、%S Hours, minutes and seconds are obtained respectively , And h:m:s Output in this format . And printf Function similar to . At this point, you can get the hours, minutes and seconds of the running time .

Realization

The original Makefile

DIR = $(shell pwd)
KER_DIR = /lib/modules/`uname -r`/build

obj-m = msg_netlink.o

all:
	make -C $(KER_DIR) M=$(PWD) modules

clean:
	make -C $(KER_DIR) M=$(PWD) clean

After modification Makefile

	DIR = $(shell pwd)
	KER_DIR = /lib/modules/`uname -r`/build
	
	START_TIME = $(shell cat /proc/uptime | awk -F "." '{print $$1}') # Makefile Get into , Get the timestamp 
	
	obj-m = msg_netlink.o
	
	all: module showruntime
	
	module: 
		make -C $(KER_DIR) M=$(PWD) modules
	
	clean:
		make -C $(KER_DIR) M=$(PWD) clean
	
	showruntime:
		@current_time=`cat /proc/uptime | awk -F "." '{print $$1}'`; \
		time_interval=`expr $${
     current_time} - $(START_TIME)`; \
		runtime=`date -u -d @$${
     time_interval} +%Hh:%Mm:%Ss`; \
		echo "######## runtime: $${runtime} ########"

analysis

Little knowledge :

1. Makefile in , call Makefile Own variables , use $ Symbol , such as Makefile Medium START_TIME.
2. Makefile in ,target Executive shell command , Variables defined , Need to use $$ Symbol call , such as showruntime Medium current_time, the reason being that shell Variables generated by the running process , Need to use $$current_time To call .
3. Again START_TIME = $(shell cat /proc/uptime | awk -F "." '{print $$1}') in , In the terminal command , obtain awk Parameter use $1 that will do , But because it is in Makefile in , call shell, So we need to use $$1 To get the segmentation value .
4. Makefile Running target in , Such as showruntime, Inside shell command , If you need to do more shell command , Need to use ; \ Symbols to continue the whole shell command , Otherwise, an error will be reported , Detailed view showruntime What's in it .
5. Makefile in @ character shell Commands can be hidden shell Command run print .
   Such as

	showruntime:
		current_time=`cat /proc/uptime | awk -F "." '{print $$1}'`; \
		time_interval=`expr $${
     current_time} - $(START_TIME)`; \
		runtime=`date -u -d @$${
     time_interval} +%Hh:%Mm:%Ss`; \
		echo "######## runtime: $${runtime} ########"

Output is as follows , You can see the whole shell The commands are printed :

make -C /lib/modules/`uname -r`/build M=/home/xxx/Desktop/xxx/test/driver modules
make[1]: Entering directory '/usr/src/linux-headers-5.13.0-41-generic'
make[1]: Leaving directory '/usr/src/linux-headers-5.13.0-41-generic'
current_time=`cat /proc/uptime | awk -F "." '{print $1}'`; \
time_interval=`expr ${
     current_time} - 6710 `; \
runtime=`date -u -d @${
     time_interval} +%Hh:%Mm:%Ss`; \
echo "######## runtime: ${runtime} ########"
######## runtime: 00h:00m:00s ########

add @ After the symbol , Only print echo The characters that come out .

	showruntime:
		@current_time=`cat /proc/uptime | awk -F "." '{print $$1}'`; \
		time_interval=`expr $${
     current_time} - $(START_TIME)`; \
		runtime=`date -u -d @$${
     time_interval} +%Hh:%Mm:%Ss`; \
		echo "######## runtime: $${runtime} ########"

Output is as follows :

make -C /lib/modules/`uname -r`/build M=/home/xxx/Desktop/xxx/test/driver modules
make[1]: Entering directory '/usr/src/linux-headers-5.13.0-41-generic'
make[1]: Leaving directory '/usr/src/linux-headers-5.13.0-41-generic'
######## runtime: 00h:00m:00s ########

The running time here is 0, Because the driver has been compiled , No changes ,make clean after , recompile , That is, you can see the running time .

make clean
ake -C /lib/modules/`uname -r`/build M=/home/xxx/Desktop/xxx/test/driver clean
make[1]: Entering directory '/usr/src/linux-headers-5.13.0-41-generic'
  CLEAN   /home/xxx/Desktop/xxx/test/driver/Module.symvers
make[1]: Leaving directory '/usr/src/linux-headers-5.13.0-41-generic'

time make #  It was used time Count the time together 

make -C /lib/modules/`uname -r`/build M=/home/xxx/Desktop/xxx/test/driver modules
make[1]: Entering directory '/usr/src/linux-headers-5.13.0-41-generic'
  CC [M]  /home/xxx/Desktop/xxx/test/driver/msg_test.o
  MODPOST /home/xxx/Desktop/xxx/test/driver/Module.symvers
  CC [M]  /home/xxx/Desktop/xxx/test/driver/msg_test.mod.o
  LD [M]  /home/xxx/Desktop/xxx/test/driver/msg_test.ko
  BTF [M] /home/xxx/Desktop/xxx/test/driver/msg_test.ko
Skipping BTF generation for /home/xxx/Desktop/xxx/test/driver/msg_test.ko due to unavailability of vmlinux
make[1]: Leaving directory '/usr/src/linux-headers-5.13.0-41-generic'
######## runtime: 00h:00m:02s ########

real    0m2.107s
user    0m0.821s
sys     0m0.301s

You can see time make Count the time , And showruntime The calculated time is 2 About seconds . experimental result ok.

summary

1. be familiar with /proc/uptime The meaning of the parameters .
2. Don't have to /proc/uptime To get the timestamp , It can be used date +%s Get the current timestamp , Instead of cat /proc/uptime
3. be familiar with date When ordered , Get the timestamp 、 Format get date .
4. Watch carefully Makefile Realized Little knowledge , There are many things involved Details , It is recommended to watch it again and again .
5. Makefile Medium target Dependence problem , Watch carefully showruntimetarget The position of .
6. Makefile in $` Symbol And $$ Symbol The difference between