Commit 658bbdda authored by Stefan Lankes's avatar Stefan Lankes Committed by Stefan Lankes
Browse files

add check if the wakeup time isn't already expired

if the time is already expired, the next timer will expire in 1ms
parent 1b16d8db
......@@ -437,12 +437,19 @@ fn calibrate_timer() {
pub fn set_oneshot_timer(wakeup_time: Option<u64>) {
const MINIMUM_DELAY: u64 = 1000; // in usec
if let Some(wt) = wakeup_time {
if processor::supports_tsc_deadline() {
// wt is the absolute wakeup time in microseconds based on processor::get_timer_ticks.
// We can simply multiply it by the processor frequency to get the absolute Time-Stamp Counter deadline
// (see processor::get_timer_ticks).
let tsc_deadline = wt * (u64::from(processor::get_frequency()));
let current_time = processor::get_timer_ticks();
let tsc_deadline = if wt >= current_time + MINIMUM_DELAY {
wt * u64::from(processor::get_frequency())
} else {
(current_time + MINIMUM_DELAY) * u64::from(processor::get_frequency())
// Enable the APIC Timer in TSC-Deadline Mode and let it start by writing to the respective MSR.
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