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36 lines
984 B
Odin
36 lines
984 B
Odin
//+private
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//+build linux
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package time
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import "core:intrinsics"
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import "core:sys/unix"
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_get_tsc_frequency :: proc "contextless" () -> (u64, bool) {
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perf_attr := unix.Perf_Event_Attr{}
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perf_attr.type = u32(unix.Perf_Type_Id.Hardware)
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perf_attr.config = u64(unix.Perf_Hardware_Id.Instructions)
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perf_attr.size = size_of(perf_attr)
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perf_attr.flags = {.Disabled, .Exclude_Kernel, .Exclude_HV}
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fd := unix.sys_perf_event_open(&perf_attr, 0, -1, -1, 0)
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if fd == -1 {
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return 0, false
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}
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defer unix.sys_close(fd)
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page_size : uint = 4096
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ret := unix.sys_mmap(nil, page_size, unix.PROT_READ, unix.MAP_SHARED, fd, 0)
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if ret < 0 && ret > -4096 {
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return 0, false
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}
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addr := rawptr(uintptr(ret))
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defer unix.sys_munmap(addr, page_size)
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event_page := (^unix.Perf_Event_mmap_Page)(addr)
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if .User_Time not_in event_page.cap.flags {
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return 0, false
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}
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frequency := u64((u128(1_000_000_000) << u128(event_page.time_shift)) / u128(event_page.time_mult))
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return frequency, true
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}
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