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runtime: time goes backwards on windows-arm64 (frequent TestGcLastTime failures) [1.17 backport] #49369

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gopherbot opened this issue Nov 4, 2021 · 4 comments
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runtime: time goes backwards on windows-arm64 (frequent TestGcLastTime failures) [1.17 backport] #49369

gopherbot opened this issue Nov 4, 2021 · 4 comments
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CherryPickApproved Used during the release process for point releases FrozenDueToAge
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Go1.17.4

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@gopherbot
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@zx2c4 requested issue #48072 to be considered for backport to the next 1.17 minor release.

@gopherbot please backport this to 1.17
@gopherbot gopherbot added the CherryPickCandidate Used during the release process for point releases label Nov 4, 2021
@gopherbot gopherbot mentioned this issue Nov 4, 2021
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@gopherbot gopherbot added this to the Go1.17.4 milestone Nov 4, 2021
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Change https://golang.org/cl/361476 mentions this issue: [release-branch.go1.17] runtime: use correct constant when computing nsec remainder

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Change https://golang.org/cl/361475 mentions this issue: [release-branch.go1.17] runtime: on windows, read nanotime with one instruction or issue barrier

@heschi heschi added the CherryPickApproved Used during the release process for point releases label Nov 24, 2021
@gopherbot gopherbot removed the CherryPickCandidate Used during the release process for point releases label Nov 24, 2021
gopherbot pushed a commit that referenced this issue Nov 24, 2021
@zx2c4 @heschi
[release-branch.go1.17] runtime: on windows, read nanotime with one i…
e347c89 
…nstruction or issue barrier

On 64-bit, this is more efficient, and on ARM64, this prevents the time
from moving backwards due to the weaker memory model. On ARM32 due to
the weaker memory model, we issue a memory barrier.

Updates #48072.
Updates #49369.

Change-Id: If4695716c3039d8af14e14808af217f5c99fc93a
Reviewed-on: https://go-review.googlesource.com/c/go/+/361057
Trust: Jason A. Donenfeld <[email protected]>
Run-TryBot: Jason A. Donenfeld <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Austin Clements <[email protected]>
Reviewed-on: https://go-review.googlesource.com/c/go/+/361475
Reviewed-by: Patrik Nyblom <[email protected]>
gopherbot pushed a commit that referenced this issue Nov 24, 2021
@zx2c4 @heschi
[release-branch.go1.17] runtime: use correct constant when computing …
4536558 
…nsec remainder

A code comment on amd64 for windows and plan9 contained a snippet for
splitting apart the sec and nsec components of a unix timestamp, with
produced assembly below, which was then cleaned up by hand. When arm64
was ported, that code snippet in the comment went through the compiler
to produce some code that was then pasted and cleaned up. Unfortunately,
the comment had a typo in it, containing 8 zeros instead of 9.

This resulted in the constant used in the assembly being wrong, spotted
by @bufflig's eagle eyes. So, this commit fixes the comment on all three
platforms, and the assembly on windows/arm64.

Updates #48072.
Fixes #49369.

Change-Id: I786fe89147328b0d25544f52c927ddfdb9f6f1cf
Reviewed-on: https://go-review.googlesource.com/c/go/+/361474
Trust: Jason A. Donenfeld <[email protected]>
Run-TryBot: Jason A. Donenfeld <[email protected]>
Reviewed-by: Patrik Nyblom <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-on: https://go-review.googlesource.com/c/go/+/361476
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Closed by merging 4536558 to release-branch.go1.17.

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Closed by merging e347c89 to release-branch.go1.17.

@golang golang locked and limited conversation to collaborators Nov 24, 2022
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