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Mbed statistics

Mbed OS provides a set of functions that you can use to capture the memory and thread statistics at runtime. mbed_stats.h declares these functions. To enable all Mbed OS platform statistics, you must enable the following Mbed OS configuration option:

{
    "target_overrides": {
        "*": {
            "platform.all-stats-enabled": true
        }
    }
}

Tip: See the documentation of the Arm Mbed configuration system for more details about mbed_app.json.

Memory statistics

You can use memory statistics functions to capture heap use, cumulative stack use or stack use for each thread at runtime. To enable memory use monitoring, you must enable the following Mbed OS configuration options:

{
    "target_overrides": {
        "*": {
            "platform.heap-stats-enabled": true,
            "platform.stack-stats-enabled": true
        }
    }
}

Note: Each malloc or calloc memory allocation call adds an overhead of 8 bytes when heap memory statistics are enabled.

Thread statistics

You can use the thread statistics function mbed_stats_thread_get_each to capture the thread ID, state, priority, name and stack information for all active threads at runtime. To enable thread monitoring, you must enable the following Mbed OS configuration options:

{
    "target_overrides": {
        "*": {
            "platform.thread-stats-enabled": true
        }
    }
}

System information

You can use the mbed_stats_sys_get function to get the CPU ID, compiler information and RAM and ROM memories on the target device. To enable system information fetching, you must enable the following Mbed OS configuration option:

{
    "target_overrides": {
        "*": {
            "platform.sys-stats-enabled": true
        }
    }
}

CPU statistics

You can use the mbed_stats_cpu_get function to get the uptime, idle time and sleep time information. Timing information available is cumulative because the system is on. Please note CPU statistics depend on the availability of the low power timer in the hardware. To enable fetching of CPU information, you must enable the following Mbed OS configuration option:

{
    "target_overrides": {
        "*": {
            "platform.cpu-stats-enabled": true
        }
    }
}

Mbed statistics function reference

Memory statistics example

/* Example usage for Debug, Assert, Error and MemoryStats 
 * Copyright (c) 2016 ARM Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "mbed.h"
#include "platform/mbed_assert.h"
#include "platform/mbed_debug.h"
#include "platform/mbed_error.h"
#include "platform/mbed_stats.h"

#define MAX_THREAD_INFO 10

mbed_stats_heap_t heap_info;
mbed_stats_stack_t stack_info[ MAX_THREAD_INFO ];
int main()
{
    debug("\nThis message is from debug function");
    debug_if(1,"\nThis message is from debug_if function");
    debug_if(0,"\nSOMETHING WRONG!!! This message from debug_if function shouldn't show on bash");
    
    printf("\nMemoryStats:");
    mbed_stats_heap_get( &heap_info );
    printf("\n\tBytes allocated currently: %d", heap_info.current_size);
    printf("\n\tMax bytes allocated at a given time: %d", heap_info.max_size);
    printf("\n\tCumulative sum of bytes ever allocated: %d", heap_info.total_size);
    printf("\n\tCurrent number of bytes allocated for the heap: %d", heap_info.reserved_size);
    printf("\n\tCurrent number of allocations: %d", heap_info.alloc_cnt);
    printf("\n\tNumber of failed allocations: %d", heap_info.alloc_fail_cnt);
    
    mbed_stats_stack_get( &stack_info[0] );
    printf("\nCumulative Stack Info:");
    printf("\n\tMaximum number of bytes used on the stack: %d", stack_info[0].max_size);
    printf("\n\tCurrent number of bytes allocated for the stack: %d", stack_info[0].reserved_size);
    printf("\n\tNumber of stacks stats accumulated in the structure: %d", stack_info[0].stack_cnt);
    
    mbed_stats_stack_get_each( stack_info, MAX_THREAD_INFO );
    printf("\nThread Stack Info:");
    for(int i=0;i < MAX_THREAD_INFO; i++) {
        if(stack_info[i].thread_id != 0) {
            printf("\n\tThread: %d", i);
            printf("\n\t\tThread Id: 0x%08X", stack_info[i].thread_id);
            printf("\n\t\tMaximum number of bytes used on the stack: %d", stack_info[i].max_size);
            printf("\n\t\tCurrent number of bytes allocated for the stack: %d", stack_info[i].reserved_size);
            printf("\n\t\tNumber of stacks stats accumulated in the structure: %d", stack_info[i].stack_cnt); 
        }        
    }
    
    printf("\nDone...\n\n");
}

Thread statistics example

#include "mbed.h"
 
#if !defined(MBED_THREAD_STATS_ENABLED)
#error "Stats not enabled"
#endif
 
#define MAX_THREAD_STATS    0x8
 
int main()
{
    mbed_stats_thread_t *stats = new mbed_stats_thread_t[MAX_THREAD_STATS];
    int count = mbed_stats_thread_get_each(stats, MAX_THREAD_STATS);
    
    for(int i = 0; i < count; i++) {
        printf("ID: 0x%x \n", stats[i].id);
        printf("Name: %s \n", stats[i].name);
        printf("State: %d \n", stats[i].state);
        printf("Priority: %d \n", stats[i].priority);
        printf("Stack Size: %d \n", stats[i].stack_size);
        printf("Stack Space: %d \n", stats[i].stack_space);
        printf("\n");
    }
    return 0;
}

System information example

#include "mbed.h"

#if !defined(MBED_SYS_STATS_ENABLED)
#error [NOT_SUPPORTED] test not supported
#endif

int main()
{
    mbed_stats_sys_t stats;
    mbed_stats_sys_get(&stats);

    printf("Mbed OS Version: %ld \n", stats.os_version);

    /* CPUID Register information
    [31:24]Implementer      0x41 = ARM
    [23:20]Variant          Major revision 0x0  =  Revision 0
    [19:16]Architecture     0xC  = Baseline Architecture
                            0xF  = Constant (Mainline Architecture?)
    [15:4]PartNO            0xC20 =  Cortex-M0
                            0xC60 = Cortex-M0+
                            0xC23 = Cortex-M3
                            0xC24 = Cortex-M4
                            0xC27 = Cortex-M7
                            0xD20 = Cortex-M23
                            0xD21 = Cortex-M33
    [3:0]Revision           Minor revision: 0x1 = Patch 1.
    */
    printf("CPU ID: 0x%x \n", stats.cpu_id);

    printf("Compiler ID: %d \n", stats.compiler_id);

    /* Compiler versions:
       ARM: PVVbbbb (P = Major; VV = Minor; bbbb = build number)
       GCC: VVRRPP  (VV = Version; RR = Revision; PP = Patch)
       IAR: VRRRPPP (V = Version; RRR = Revision; PPP = Patch)
    */
    printf("Compiler Version: %d \n", stats.compiler_version);

    return 0;
}

CPU statistics example

#include "mbed.h"

#if !defined(MBED_CPU_STATS_ENABLED) || !defined(DEVICE_LPTICKER) || !defined(DEVICE_SLEEP)
#error [NOT_SUPPORTED] test not supported
#endif

DigitalOut led1(LED1);

#define MAX_THREAD_STACK        384
#define SAMPLE_TIME             1000
#define LOOP_TIME               3000

uint64_t prev_idle_time = 0;
int32_t wait_time = 5000;

void busy_thread()
{
    volatile uint64_t i = ~0;

    while(i--) {
        led1 = !led1;
        wait_us(wait_time);
    }
}

void print_stats()
{
    mbed_stats_cpu_t stats;
    mbed_stats_cpu_get(&stats);

    printf("%-20lld", stats.uptime);
    printf("%-20lld", stats.idle_time);
    printf("%-20lld", stats.sleep_time);
    printf("%-20lld\n", stats.deep_sleep_time);
}

int main()
{
    // Request the shared queue
    EventQueue *stats_queue = mbed_event_queue();
    Thread *thread;
    int id;

    id = stats_queue->call_every(SAMPLE_TIME, print_stats);
    printf("%-20s%-20s%-20s%-20s\n", "Uptime", "Idle Time", "Sleep time", "DeepSleep time");

    thread = new Thread(osPriorityNormal, MAX_THREAD_STACK);
    thread->start(busy_thread);

    // Steadily increase the system load
    for (int count = 1; ; count++) {
        Thread::wait(LOOP_TIME);
        if (wait_time <= 0) {
            break;
        }
        wait_time -= 1000;
    }
    thread->terminate();
    stats_queue->cancel(id);
    return 0;
}

CPU usage example

#include "mbed.h"

#if !defined(MBED_CPU_STATS_ENABLED) || !defined(DEVICE_LPTICKER) || !defined(DEVICE_SLEEP)
#error [NOT_SUPPORTED] test not supported
#endif

DigitalOut led1(LED1);

#define MAX_THREAD_STACK        384
#define SAMPLE_TIME             2000    // msec
#define LOOP_TIME               3000    // msec

uint64_t prev_idle_time = 0;
int32_t wait_time = 5000;      // usec

void busy_thread()
{
    volatile uint64_t i = ~0;

    while(i--) {
        led1 = !led1;
        wait_us(wait_time);
    }
}

void calc_cpu_usage()
{
    mbed_stats_cpu_t stats;
    mbed_stats_cpu_get(&stats);

    uint64_t diff = (stats.idle_time - prev_idle_time);
    uint8_t idle = (diff * 100) / (SAMPLE_TIME*1000);    // usec;
    uint8_t usage = 100 - ((diff * 100) / (SAMPLE_TIME*1000));    // usec;;
    prev_idle_time = stats.idle_time;

    printf("Idle: %d Usage: %d \n", idle, usage);
}

int main()
{
    // Request the shared queue
    EventQueue *stats_queue = mbed_event_queue();
    Thread *thread;
    int id;

    id = stats_queue->call_every(SAMPLE_TIME, calc_cpu_usage);
    thread = new Thread(osPriorityNormal, MAX_THREAD_STACK);
    thread->start(busy_thread);

    // Steadily increase the system load
    for (int count = 1; ; count++) {
        Thread::wait(LOOP_TIME);
        if (wait_time <= 0) {
            break;
        }
        wait_time -= 1000;  // usec
    }
    thread->terminate();
    stats_queue->cancel(id);
    return 0;
}

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