Microbenchmark - Fix precision loss in kernel launch overhead benchmark#773
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alephpiece wants to merge 1 commit intomicrosoft:mainfrom
Open
Microbenchmark - Fix precision loss in kernel launch overhead benchmark#773alephpiece wants to merge 1 commit intomicrosoft:mainfrom
alephpiece wants to merge 1 commit intomicrosoft:mainfrom
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guoshzhao
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Thanks @alephpiece for pointing out this issue. We will verify and review this PR. |
polarG
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Jan 22, 2026
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Pull request overview
This PR fixes a precision loss bug in the kernel launch overhead microbenchmark where integer division was causing microsecond components to be truncated to zero for sub-millisecond measurements.
Changes:
- Refactored time calculation from expanding then subtracting to subtracting then expanding, using floating-point arithmetic throughout
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Description
The original code uses integer division in the time calculation: (end_tv.tv_usec) / 1000. Since an empty kernel launch overhead is typically very small (often less than 1ms), this integer division truncates the microsecond component to 0, leading to significant precision loss and incorrect results.
Major Revision