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runtime: use clock_gettime instead of gettimeofday on Darwin #25633

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randall77 opened this issue May 29, 2018 · 6 comments
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runtime: use clock_gettime instead of gettimeofday on Darwin #25633

randall77 opened this issue May 29, 2018 · 6 comments
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FrozenDueToAge NeedsFix The path to resolution is known, but the work has not been done. OS-Darwin
Milestone
Go1.16

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@randall77
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clock_gettime has higher resolution, we should use it if available.
It is not guaranteed to be available until Darwin 10.12. This issue is on hold until that is our minimum Darwin version.

We could do this now but it would require making the choice at runtime. That seems difficult - we'd need to use the Darwin equivalent of dlopen/dlsym to query the existence of, and call, clock_gettime.
@randall77 randall77 added OS-Darwin NeedsFix The path to resolution is known, but the work has not been done. labels May 29, 2018
@randall77 randall77 added this to the Go1.12 milestone May 29, 2018
@randall77 randall77 self-assigned this May 29, 2018
@randall77 randall77 modified the milestones: Go1.12, Unplanned Sep 19, 2018
@gopherbot
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Change https://golang.org/cl/161721 mentions this issue: unix: add ClockGettime on darwin/amd64

gopherbot pushed a commit to golang/sys that referenced this issue Feb 9, 2019
@josharian
unix: add ClockGettime on darwin/amd64
3b52091 
Updates golang/go#25633

Change-Id: I20ff2d0cda642fb7b155d3ae06499e8c0ef0a2b2
Reviewed-on: https://go-review.googlesource.com/c/161721
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
@randall77
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Go 1.13 requires Darwin 1.11 or newer. Getting closer...

@randall77
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Go 1.15 will require 10.12. Setting that milestone.

@randall77 randall77 modified the milestones: Unplanned, Go1.15 Jan 30, 2020
@ianlancetaylor ianlancetaylor modified the milestones: Go1.15, Go1.16 May 19, 2020
@gopherbot
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Change https://golang.org/cl/270918 mentions this issue: runtime: use clock_gettime instead of gettimeofday on darwin

@bradfitz
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@tklauser, any positive performance improvements as a result of this? I seem to recall another bug where getting the time on macOS was really slow for some reason.

@tklauser
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@bradfitz I didn't see any performance improvements. The benchmarks seem more or less unchanged (macOS 10.15 on 1.6 GHz Dual-Core Intel Core i5):

name           old time/op  new time/op  delta
Now-4          83.3ns ± 4%  80.9ns ± 2%  -2.81%  (p=0.009 n=10+10)
NowUnixNano-4  85.3ns ± 4%  85.1ns ± 3%    ~     (p=1.000 n=10+10)

Results seems to be a bit inconsistent though, for some runs I also got slightly increased numbers (around +2%).

@xor-gate xor-gate mentioned this issue Mar 2, 2021
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FrozenDueToAge NeedsFix The path to resolution is known, but the work has not been done. OS-Darwin
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@bradfitz @tklauser @ianlancetaylor @randall77 @gopherbot