With b.Loop() in place, the time measurement of loop scaling could be improved to be tighter. By identifying the first call to b.Loop(), we can avoid measuring the expensive ramp-up time by reset the timer tightly before the loop starts. The remaining loop scaling logic of b.N style loop is largely reused.
For #61515.
Change-Id: Ia7b8f0a8838f57c00ac6c5ef779d86f8d713c9b6
Reviewed-on: https://go-review.googlesource.com/c/go/+/612835
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Junyang Shao <shaojunyang@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
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