Blue Pill stm32 SysTick problem

[NCHU-Jimmy]

Hello, I recently encountered a problem while testing the SysTick on the Blue Pill. I am using the AHB/8 clock (9 MHz) to toggle the state of PA1 every second. However, I observed that the state changes approximately every 333 ms instead. Could this be due to an issue with my code, or is the AHB clock not actually running at 72 MHz?
I would appreciate any help, thank you!

#include "stm32f10x.h"

// Custom system initialization function
void MySystemInit(void) {

    // Enable clock for GPIOA
    RCC->APB2ENR |= RCC_APB2ENR_IOPAEN;  

    // Configure PA1 as push-pull output
    GPIOA->CRL &= ~(GPIO_CRL_MODE1 | GPIO_CRL_CNF1);  
    GPIOA->CRL |= GPIO_CRL_MODE1_1;  // Set output speed to 2 MHz

    // Configure SysTick timer
    SysTick->CTRL &= ~SysTick_CTRL_CLKSOURCE_Msk;  // Use AHB/8 as the clock source for SysTick
    SysTick->LOAD = 9000000 - 1;  // Set reload value for 1-second interval ( AHB/8 clock)
    SysTick->VAL = 0;  // Clear current value
    NVIC_SetPriority (SysTick_IRQn, (1UL << __NVIC_PRIO_BITS) - 1UL);  // Set SysTick interrupt priority to lowest
    SysTick->CTRL  =  SysTick_CTRL_TICKINT_Msk | SysTick_CTRL_ENABLE_Msk;  // Enable SysTick interrupt and counter
}

// SysTick interrupt handler
void SysTick_Handler(void) {
   GPIOA->ODR ^= (1 << 1);  // Toggle PA1 (toggle LED or signal)
}

// Main program
int main(void) {
    MySystemInit();  // Initialize system and peripherals

    while (1) {
        // Main loop - no additional actions are needed, as SysTick interrupt handles PA1 toggling
    }
}