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shuffle tsc around a little

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This commit is contained in:
Colin Davidson
2023-02-22 12:28:24 -08:00
parent 8e5e43f335
commit c6f463b8c9
1 changed files with 13 additions and 15 deletions
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core/time/perf.odin
+13 -15
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@@ -41,6 +41,7 @@ _tick_duration_end :: proc "contextless" (d: ^Duration, t: Tick) {
} }
when ODIN_ARCH == .amd64 { when ODIN_ARCH == .amd64 {
@(private)
x86_has_invariant_tsc :: proc "contextless" () -> bool { x86_has_invariant_tsc :: proc "contextless" () -> bool {
eax, _, _, _ := intrinsics.x86_cpuid(0x80_000_000, 0) eax, _, _, _ := intrinsics.x86_cpuid(0x80_000_000, 0)
@@ -63,27 +64,24 @@ has_invariant_tsc :: proc "contextless" () -> bool {
return false return false
} }
_get_tsc_frequency_fallback :: proc "contextless" () -> u64 { tsc_frequency :: proc "contextless" () -> (u64, bool) {
tsc_begin := intrinsics.read_cycle_counter()
tick_begin := tick_now()
sleep(2 * Second)
tsc_end := intrinsics.read_cycle_counter()
tick_end := tick_now()
time_diff := u128(duration_nanoseconds(tick_diff(tick_begin, tick_end)))
return u64((u128(tsc_end - tsc_begin) * 1_000_000_000) / time_diff)
}
get_tsc_frequency :: proc "contextless" () -> (u64, bool) {
if !has_invariant_tsc() { if !has_invariant_tsc() {
return 0, false return 0, false
} }
hz, ok := _get_tsc_frequency() hz, ok := _get_tsc_frequency()
if !ok { if !ok {
hz = _get_tsc_frequency_fallback() // fallback to approximate TSC
tsc_begin := intrinsics.read_cycle_counter()
tick_begin := tick_now()
sleep(2 * Second)
tsc_end := intrinsics.read_cycle_counter()
tick_end := tick_now()
time_diff := u128(duration_nanoseconds(tick_diff(tick_begin, tick_end)))
hz = u64((u128(tsc_end - tsc_begin) * 1_000_000_000) / time_diff)
} }
return hz, true return hz, true