perf_counter (v1.9.8)

A dedicated performance counter for Cortex-M Systick. It shares the SysTick with users' original SysTick function(s) without interfering with it. This library will bring new functionalities, such as performance counter, delay_us and clock() service defined in time.h.

Features:

• Measure CPU cycles for specified code segment

• [NEW] Enhanced measurement services for RTOS

  • Measures RAW / True cycles used for specified code segment inside a thread, i.e. scheduling cost are removed.
  • Measure RAW/True cycles used for a data-process-path across multiple threads.

• Easy to use

  • Helper macros: __cycleof__() , __super_loop_monitor__() etc.
  • Helper functions: start_cycle_counter(), stop_cycle_counter() etc.

• Support ALL Cortex-M processors

  • Including Cortex-M85 and Star-MC1

• Provide Free Services

  • Do NOT interfering with existing SysTick based applications

• Support ALL arm compilers

  • Arm Compiler 5 (armcc), Arm Compiler 6 (armclang)
  • arm gcc
  • LLVM
  • IAR

• Simplified Deployment

  • Drag-and-Drop deployment for Arm Compiler 5 and Arm Compiler 6.
  • CMSIS-Pack is available
  • RT-Thread package is avaialble

• Time based services

  • delay_us() and delay_ms()
  • Provides Timestamp services via get_system_ticks() and get_system_ms()

• Support both RTOS and bare-metal environments

• Utilities for C language enhancement

  • Macros to detect compilers, e.g. __IS_COMPILER_ARM_COMPILER_6__, __IS_COMPILER_LLVM__ etc.
  • Macro to create atomicity for specified code block, i.e. __IRQ_SAFE{...}
  • Helper macros for C language extension:
    • VB like with()
    • foreach(), dimof(), CONNECT()
    • C# like using()
    • simple overload feature of OOPC made out of ANSI-C99, __PLOOC_VA_NUM_ARGS()
    • ...

1. How To Use

1.1 Measure CPU cycles for specified code segment

You can measure specified code segment with a macro helper __cycleof__(), it is a wrapper of get_system_ticks().

Syntax:

__cycleof__(<Description String for the target>, [User Code, see ref 1]) {
    //! target code segment of measurement
    ...
}

Here, [ref 1] is a small user code to read the measurement result via a local variable __cycle_count__ for perl lovers, you can also use "_" to read the result. This User Code is optional. If you don't put anything here, the measured result will be shown with a printf().

Example 1: Simple measurement with printf

    __cycleof__() {
        foreach(example_lv0_t, s_tItem, ptItem) {
            printf("Processing item with ID = %d\r\n", _->chID);
        }
    }

You will see the measured result in console:

Example 2: Read measured result via __cycle_counter__

    int32_t iCycleResult = 0;

    /* measure cycles and store it in a dedicated variable without printf */
    __cycleof__("delay_us(1000ul)", 
        /* insert code to __cycleof__ body, "{}" can be omitted  */
        {
            iCycleResult = __cycle_count__;   /*< "__cycle_count__" stores the result */
        }) {
        delay_us(1000ul);
    }

    printf("\r\n delay_us(1000ul) takes %d cycles\r\n", (int)iCycleResult);

The result is read out from __cycle_count__and used in other place:

1.2 Timestamp

You can get the system timestamp (since the initialization of perf_counter service) via function get_system_ticks() and get_system_ms().

NOTE: The get_system_ms() is NOT a wrapper of the function get_system_ticks().

There are various way to take advantage of those functions.

Example 3: Use get_system_ms() as random seed

#include <stdio.h>
#include <stdlib.h>
#include "perf_counter.h"

int main (void) 
{
   int i, n;
   
   n = 5;
   
   /* Intializes random number generator */
   srand((unsigned) get_system_ticks());

   /* Print 5 random numbers from 0 to 1024 */
   for( i = 0 ; i < n ; i++ ) {
      printf("%d\n", rand() & 0x3FF);
   }
   
   return(0);
}

Example 4: Measure CPU cycles

    do {
        int64_t tStart = get_system_ticks();
        __IRQ_SAFE {
            printf("no interrupt \r\n");
        }
        printf("used clock cycle: %d", (int32_t)(get_system_ticks() - tStart));
    } while(0);

This example shows how to use the delta value of get_system_ticks() to measure the CPU cycles used by specified code segment. In fact, the __cycleof__() is implemented in the same way:

#define __cycleof__(__STR, ...)                                                 \
            using(int64_t _ = get_system_ticks(), __cycle_count__ = _,          \
                _=_, {                                                          \
                _ = get_system_ticks() - _;                                     \
                __cycle_count__ = _;                                            \
                if (__PLOOC_VA_NUM_ARGS(__VA_ARGS__) == 0) {                    \
                    printf("\r\n");                                             \
                    printf("-[Cycle Report]");                                  \
                    printf("--------------------------------------------\r\n"); \
                    printf(__STR " total cycle count: %d [%08x]\r\n",           \
                            (int)_, (int)_);                                    \
                } else {                                                        \
                    __VA_ARGS__                                                 \
                };                                                              \
            })

2. How To Deploy

2.1 Generic(Default) method for all compilers

2.1.1 For Bare-metal:

1. Clone the code to your local with following command lines:

git clone https://github.com/GorgonMeducer/perf_counter.git

2. Add including path for perf_counter folder
3. Add perf_counter.c to your compilation
4. Include perf_counter.h in corresponding c source file:

#include "perf_counter.h"

5. Make sure your system contains the CMSIS (with a version 5.7.0 or above) as perf_counter.h includes cmsis_compiler.h.
6. Call the function user_code_insert_to_systick_handler() in your SysTick_Handler()

void SysTick_Handler(void)
{
    ...
    user_code_insert_to_systick_handler();
    ...
}

7. Make sure the SystemCoreClock is updated with the same value as CPU frequency.
8. IMPORTANT: Make sure the SysTick_CTRL_CLKSOURCE_Msk bit ( bit 2) of SysTick->CTRL register is 1 that means SysTick runs with the same clock source as the target Cortex-M processor.
9. Initialize the perf_counter with boolean value that indicates whether the user applications and/or RTOS have already occupied the SysTick.

void main(void)
{
    //! setup system clock 
    
    /*! \brief Update SystemCoreClock with the latest CPU frequency
     *!        If the function doesn't exist or doesn't work correctly,
     *!        Please update SystemCoreClock directly with the correct
     *!        system frequency in Hz.
     *!       
     *!        extern volatile uint32_t SystemCoreClock;
     */
    SystemCoreClockUpdate();
    
    /*! \brief initialize perf_counter() and pass true if SysTick is 
     *!        occupied by user applications or RTOS, otherwise pass
     *!        false. 
     */
    init_cycle_counter(true);
    
    ...
    while(1) {
        ...
    }
}

10. IMPORTANT: Please enable GNU extension in your compiler. For GCC and CLANG, it is --std=gnu99 or --std=gnu11, and for other compilers, please check the user manual first. Failed to do so, you will not only trigger the warning in perf_counter.h, but also lose the function correctness of __cycleof__() and __super_loop_monitor__(), because __PLOOC_VA_NUM_ARGS() isn't report 0 when passed with no argument.

#if __PLOOC_VA_NUM_ARGS() != 0
#warning Please enable GNC extensions, it is required by __cycleof__() and \
__super_loop_monitor__()
#endif

11. It is nice to add macro definition __PERF_COUNTER__ to your project GLOBALLY. It helps other module to detect the existence of perf_counter. For Example, LVGL lv_conf_cmsis.h use this macro to detect perf_counter and uses get_system_ms() to implement lv_tick_get().

Enjoy !

2.2 Use cmsis-pack in MDK

1. Download the cmsis-pack from cmsis-pack folder. It is a file with name GorgonMeducer.perf_counter.<version>.pack, for example GorgonMeducer.perf_counter.1.9.4.pack

2. Double click it to install this cmsis-pack. Once finished, you can find it in your Pack-Installer:

   In the future, you can pull the latest version of perf_counter from the menu Packs->Check For Updates as shown below:

   

3. Open the RTE management window, find the Utilities and select the Core inside perf_counter as shown below:

4. Include perf_counter.h in corresponding c source file:

#include "perf_counter.h"

5. Make sure your system contains the CMSIS (with a version 5.7.0 or above) as perf_counter.h includes cmsis_compiler.h. Usually, you should do this with RTE as shown below:

6. Make sure the SystemCoreClock is updated with the same value as CPU frequency.
7. IMPORTANT: Make sure the SysTick_CTRL_CLKSOURCE_Msk bit ( bit 2) of SysTick->CTRL register is 1 that means SysTick runs with the same clock source as the target Cortex-M processor.
8. Initialize the perf_counter with boolean value that indicates whether the user applications and/or RTOS have already occupied the SysTick.

void main(void)
{
    //! setup system clock 
    
    /*! \brief Update SystemCoreClock with the latest CPU frequency
     *!        If the function doesn't exist or doesn't work correctly,
     *!        Please update SystemCoreClock directly with the correct
     *!        system frequency in Hz.
     *!       
     *!        extern volatile uint32_t SystemCoreClock;
     */
    SystemCoreClockUpdate();
    
    /*! \brief initialize perf_counter() and pass true if SysTick is 
     *!        occupied by user applications or RTOS, otherwise pass
     *!        false. 
     */
    init_cycle_counter(true);
    
    ...
    while(1) {
        ...
    }
}

9. IMPORTANT: Please enable GNU extension in your compiler.

   For Arm Compiler 5, please select both C99 mode and GNU extensions in the Option for target dialog as shown below:

For Arm Compiler 6, please select gnu99 or gnu11 in Language C drop-list as shown below:

Failed to do so, you will not only trigger the warning in perf_counter.h, but also lose the function correctness of __cycleof__() and __super_loop_monitor__(), because __PLOOC_VA_NUM_ARGS() isn't report 0 when passed with no argument.

#if __PLOOC_VA_NUM_ARGS() != 0
#warning Please enable GNC extensions, it is required by __cycleof__() and \
__super_loop_monitor__()
#endif

2.3 Use perf_counter in RT-Thread RTOS

perf_counter has registered as one of the RT-Thread software packages, which locats in system category. In ENV or RT-Thread Studio, you just need to simply enable cputime framework. RT-Thread will automatically enable perf_counter if you are using Cortex-M architecture.

Enjoy !

3. FAQ

3.1 Why I see Undefined symbol $Super$$SysTick_Handler

This error usually pops-up in Arm Compiler 5 and Arm Compiler 6, it is because you haven't implement any non-weak Systick_Handler(). Please provide an EMPTY one in any c source file to solve this problem:

void SysTick_Handler(void)
{
}

NOTE: If you deploy perf_counter using cmsis-pack and encounter this issue, please DO NOT call function user_code_insert_to_systick_handler() in this should-be-empty SysTick_Handler().

4. License

Performance Counter for Cortex-M, a.k.a. perf_counter is under Apache 2.0 license.