Upstream Go tip has updated its version to 1.19, so we need to bump these build
tags to allow tip testing.
This CL bumps the minimum version in pkg/sync/runtime_amd64.s from 1.8 to 1.14.
The offset was different prior to Go 1.14.
Ideally we'll get checklinkname (or equivalent) to check these remaining unsafe
uses (like internal struct field offsets) soon.
For golang/go#51445.
PiperOrigin-RevId: 433304124
Some synchronization patterns require the ability to simultaneously wake and
sleep a goroutine. For the sleep package, this is the case when a waker must be
asserted when a subsequent fetch is imminent.
Currently, this operation results in significant P churn in the runtime, which
ping-pongs execution between multiple system threads and cores and consumes a
significant amount of host CPU (and because of the context switches, this can
be significant worse with mitigations for side channel vulnerabilities).
The solution is to introduce a dedicated mechanism for a synchronous switch
which does not wake another runtime P (see golang/go#32113). This can be used
by the `AssertAndFetch` API in the sleep package.
The benchmark results for this package are very similiar to raw channel
operations for all cases, with the exception of operations that do not wait.
The primary advantage is more precise control over scheduling. This will be
used in a subsequent change.
```
BenchmarkGoAssertNonWaiting
BenchmarkGoAssertNonWaiting-8 261364384 4.976 ns/op
BenchmarkGoSingleSelect
BenchmarkGoSingleSelect-8 20946358 57.77 ns/op
BenchmarkGoMultiSelect
BenchmarkGoMultiSelect-8 6071697 197.0 ns/op
BenchmarkGoWaitOnSingleSelect
BenchmarkGoWaitOnSingleSelect-8 4978051 235.4 ns/op
BenchmarkGoWaitOnMultiSelect
BenchmarkGoWaitOnMultiSelect-8 2309224 520.2 ns/op
BenchmarkSleeperAssertNonWaiting
BenchmarkSleeperAssertNonWaiting-8 447325033 2.657 ns/op
BenchmarkSleeperSingleSelect
BenchmarkSleeperSingleSelect-8 21488844 55.19 ns/op
BenchmarkSleeperMultiSelect
BenchmarkSleeperMultiSelect-8 21851674 54.89 ns/op
BenchmarkSleeperWaitOnSingleSelect
BenchmarkSleeperWaitOnSingleSelect-8 2860327 416.4 ns/op
BenchmarkSleeperWaitOnSingleSelectSync
BenchmarkSleeperWaitOnSingleSelectSync-8 2741733 427.1 ns/op
BenchmarkSleeperWaitOnMultiSelect
BenchmarkSleeperWaitOnMultiSelect-8 2867484 418.1 ns/op
BenchmarkSleeperWaitOnMultiSelectSync
BenchmarkSleeperWaitOnMultiSelectSync-8 2789158 427.9 ns/op
```
PiperOrigin-RevId: 415581417
Michael Pratt
Adin Scannell