框架代码里timer的（也许算是）bug

[Ayana-chan]

/// get current time in milliseconds
#[allow(dead_code)]
pub fn get_time_ms() -> usize {
    println!("DEBUG: get_time_ms: {} / {}", time::read(), (CLOCK_FREQ / MSEC_PER_SEC));
    time::read() / (CLOCK_FREQ / MSEC_PER_SEC)
}

/// get current time in microseconds
#[allow(dead_code)]
pub fn get_time_us() -> usize {
    println!("DEBUG: get_time_us: {} / {}", time::read(), (CLOCK_FREQ / MICRO_PER_SEC));
    time::read() / (CLOCK_FREQ / MICRO_PER_SEC)
}

一旦代码里面（如taskinfo）混用get_time_ms和get_time_us就会出问题！因为时间计算是先获得时间再除以 (CLOCK_FREQ / xxxx_PER_SEC);但是， (CLOCK_FREQ / MICRO_PER_SE)会损失很大的精度：12_500_000 / 1_000_000 = 12，导致get_time_us结果偏大

[lighkLife]

这样写会减少损失（但会更容易溢出）

/// get current time in milliseconds
    time::read() * MSEC_PER_SEC / (CLOCK_FREQ )

/// get current time in microseconds
    time::read() * MICRO_PER_SEC / (CLOCK_FREQ )