EasyPThread

Real-time C library for thread-based time and task management using pthreads, with built-in statistical analysis.

Prerequisite • Getting Started • Library Functions • Example

Prerequisite

• CMake 3.1+ - A cross-platform, open-source build system.

Getting Started

To get started with EasyPThread, follow these simple steps:

1. Clone the repository (e.g., with HTTPS URLs):

   git clone https://github.com/liviobisogni/lib-easypthread

2. Navigate to the repository directory:

   cd lib-easypthread

3. Build the EasyPThread library by running the installation script in the root directory of the repository:

   ./build_lib.sh

   This will generate the library file libeasypthread.a in the build directory.

4. Include the header files easy_pthread_time.h and easy_pthread_task.h in your project source code:

   #include "easy_pthread_time.h"
   #include "easy_pthread_task.h"

5. Link your project with the libeasypthread.a library file by passing the following flag to the compiler:

   -L/path/to/lib-easypthread/build -libeasypthread

where /path/to/lib-easypthread/build is the path to the build directory of the EasyPThread repository.

6. Use the EasyPThread library functions in your code. See the Library Functions section for more information on available functions.

The Tanks Simulator project provides an example of how EasyPThread can be used in a concrete case.

Library Functions

Time-Related Functions (easy_pthread_time.h)

• time_copy

   void time_copy(struct timespec *td, struct timespec ts)

  Copies a source time variable ts to a destination time variable pointed by td.

  • Parameters
    • td A pointer to a struct timespec variable representing the destination time.
    • ts A struct timespec variable representing the source time.

• time_add_ms

   void time_add_ms(struct timespec *t, int ms)

  Adds a value ms (expressed in milliseconds) to the time variable pointed by t.

  • Parameters
    • t A pointer to a struct timespec variable representing the time to be incremented.
    • ms An integer representing the value to be added to the time variable in milliseconds.

• time_cmp

   int time_cmp(struct timespec t1, struct timespec t2)

  Compares two time variables t1 and t2 and returns the result of the comparison.

  • Parameters
    • t1 A struct timespec variable representing the first time.
    • t2 A struct timespec variable representing the second time.
  • Returns
    • An integer representing the result of the comparison:
      • 0 if t1 = t2
      • 1 if t1 > t2
      • -1 if t1 < t2

• timespec2ms

   double timespec2ms(struct timespec t)

  Converts a timespec structure variable t to milliseconds.

  • Parameters
    • t A struct timespec variable representing the time to convert.
  • Returns
    • A double value representing the time in milliseconds.

• get_time_diff_in_ms

   double get_time_diff_in_ms(struct timespec *t1, struct timespec *t2)

  Computes the difference between two timespec structure variables t1 and t2, both expressed in milliseconds.

  • Parameters
    • t1 A pointer to a struct timespec variable representing the first time.
    • t2 A pointer to a struct timespec variable representing the second time.
  • Returns
    • A double value representing the time difference in milliseconds.

Task-Related Functions (easy_pthread_task.h)

• ...

An example

A use case (taken from Tanks Simulator):

foo@bar:~$

# [...] other task WCET estimations [...]

******************************************
************ WCET ESTIMATION: ************
************  Graphics Task   ************
******************************************
Loop length:			82671 cycles
Deadline misses:		2
NOTE: Times are expressed in milliseconds.
Response time analysis:
	Average (AORT):		1,820858
	Maximum (WORT):		34,920520
	Minimum (BORT):		1,273668
	Total:			150532,141663
	Standard deviation:	0,464532
	Utilization factor:	4,552145%
20 worst response times
	1)	rt[82616]:	34,920520
	2)	rt[79819]:	24,135712
	3)	rt[57319]:	22,416414
	4)	rt[25819]:	12,704050
	5)	rt[63808]:	9,537036
	6)	rt[80760]:	9,517341
	7)	rt[82587]:	9,319828
	8)	rt[58991]:	8,379423
	9)	rt[70820]:	8,252726
	10)	rt[20291]:	8,187747
	11)	rt[63319]:	8,085694
	12)	rt[42803]:	8,038885
	13)	rt[46521]:	7.970052
	14)	rt[69319]:	7,946617
	15)	rt[68261]:	7,890043
	16)	rt[54126]:	7,748464
	17)	rt[50348]:	7.742843
	18)	rt[50717]:	7,734707
	19)	rt[78320]:	7,603784
	20)	rt[61391]:	7,584347



******************************************
*****        TANKS SIMULATOR:        *****
******************************************
Total elapsed time:			3306,919036 s

Utilization factor:			5,17%

Deadline misses:
		Task 1	(Tank[1]):	0
		Task 2	(Tank[2]):	0
		Task 3	(Tank[3]):	0
		Task 4	(Tank[4]):	0
		Task 5	(Tank[5]):	0
		Task 6	(Sensor[1]):	0
		Task 7	(Sensor[2]):	1
		Task 8	(Sensor[3]):	0
		Task 9	(Sensor[4]):	0
		Task 10	(Sensor[5]):	0
		Task 11	(User):		1
		Task 12	(Graphics):	2