Project (cpu_usage.c) does not work properly with TM4C timer set 120Mhz SYSCLK or 16mHz PIOSC time bases.

Oddly (cpu_usage.c) utility works great when it was loaded on 50Mhz LM3S MCU and called from a 5ms SYSTICK as shown below.

Symptoms are it reports a constant CPU usage speed at all times unless the usage call is placed in a 1 second polling timer handler versus 5-10ms polling of Systick handler. At which point there is drastic CPU usage swing from 19% to 3%, suspect is where the application reloads. That swing is not normally detected in 5-10ms polling intervals but is in 1 second polling intervals. Seemingly It should be able to work from Systick 5 or 10ms calls. 

It seems the 120Mhz SYSCLK may be suspect but reducing the value of the selected timer load count (0xFFFF.FFFF) to say 0x001F.FFFF makes the count cycle as noted above. The odd thing is there is no timer interrupt but it worked by calculating the time between Systick calls.

Has anyone ever tried to get (cpu_usage.c) to work with TM4C other than me? 

BTW have added 2 more timers into the configuration up to GPTM-7.

// Initialize the processor useage routine with Timer-7.
CPUUsageInit(TIMER_CLOCK_PIOSC, APP_TICKS_PER_SEC, 7);//200 AppTicks

Systick call: 

// Compute the new value for the processor usage. 	
g_ui32CPUUsage = (CPUUsageTick() +  786480) / 157286;

//*****************************************************************************
//
// The peripheral identifier for the timer modules that could be used for
// tracking CPU utilization.
//
//*****************************************************************************
static uint32_t g_pui32CPUUsageTimerPeriph[8] =
{
    SYSCTL_PERIPH_TIMER0, SYSCTL_PERIPH_TIMER1, SYSCTL_PERIPH_TIMER2,
    SYSCTL_PERIPH_TIMER3, SYSCTL_PERIPH_TIMER4, SYSCTL_PERIPH_TIMER5,
    SYSCTL_PERIPH_TIMER6, SYSCTL_PERIPH_TIMER7
};

//*****************************************************************************
//
// The base address of the timer modules that could be used for tracking CPU
// utilization.
//
//*****************************************************************************
static uint32_t g_pui32CPUUsageTimerBase[8] =
{
    TIMER0_BASE, TIMER1_BASE, TIMER2_BASE, TIMER3_BASE, TIMER4_BASE,
    TIMER5_BASE, TIMER6_BASE, TIMER7_BASE
};