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      "post_id": "2060730425929080874",
      "author": "NOTimothyLottes",
      "handle": "NOTimothyLottes",
      "text": "Renovating CPU clock code. I'm assuming x86-64 TSC is always >= 1 GHz so that conversion of clock counter diff to nanoseconds is simply a MUL instruction fetching the RDX high 64-bit result (of the 128-bit computed). But figuring out how to do the inline asm was a pain.",
      "timestamp": "2026-05-30 14:29:54",
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      "post_id": "2060742129190568413",
      "author": "NOTimothyLottes",
      "handle": "NOTimothyLottes",
      "text": "Looks like NtQuerySystemInformation() with SystemHypervisorSharedPageInformation (aka 0xc5) gives 64-bit scalar for TSC that converts time to units of 10 MHz. So the smart way is to work in units of TSC, then do a subtraction of TSC terms, then MULHI to get {ms, us, or ns} time",
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      "post_id": "2060752921092833490",
      "author": "NOTimothyLottes",
      "handle": "NOTimothyLottes",
      "text": "https://gist.github.com/pmttavara/6f06fc5c7679c07375483b06bb77430c - A great reference for getting TSC scaling multipliers on Linux and Windows",
      "timestamp": "2026-05-30 15:59:17",
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      "post_id": "2060885487858880689",
      "author": "Robert Clausecker",
      "handle": "FUZxxl",
      "text": "@NOTimothyLottes If you do the multiply in uint128_t and then right-shift by 64 places, the compiler should do the right thing.",
      "timestamp": "2026-05-31 00:46:04",
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      "post_id": "2060898306851516562",
      "author": "NOTimothyLottes",
      "handle": "NOTimothyLottes",
      "text": "@FUZxxl “Should” is exactly why I prefer the actual instruction instrinsics or just inline asm (which is what I use on C CPU land)",
      "timestamp": "2026-05-31 01:37:00",
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      "post_id": "2061000558698197386",
      "author": "Robert Clausecker",
      "handle": "FUZxxl",
      "text": "@NOTimothyLottes Have fun with a solution that the compiler optimises worse and that is not portable.",
      "timestamp": "2026-05-31 08:23:19",
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