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go/src/runtime/timeasm.go

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time: optimize Now on darwin, windows Fetch both monotonic and wall time together when possible. Avoids skew and is cheaper. Also shave a few ns off in conversion in package time. Compared to current implementation (after monotonic changes): name old time/op new time/op delta Now 19.6ns ± 1% 9.7ns ± 1% -50.63% (p=0.000 n=41+49) darwin/amd64 Now 23.5ns ± 4% 10.6ns ± 5% -54.61% (p=0.000 n=30+28) windows/amd64 Now 54.5ns ± 5% 29.8ns ± 9% -45.40% (p=0.000 n=27+29) windows/386 More importantly, compared to Go 1.8: name old time/op new time/op delta Now 9.5ns ± 1% 9.7ns ± 1% +1.94% (p=0.000 n=41+49) darwin/amd64 Now 12.9ns ± 5% 10.6ns ± 5% -17.73% (p=0.000 n=30+28) windows/amd64 Now 15.3ns ± 5% 29.8ns ± 9% +94.36% (p=0.000 n=30+29) windows/386 This brings time.Now back in line with Go 1.8 on darwin/amd64 and windows/amd64. It's not obvious why windows/386 is still noticeably worse than Go 1.8, but it's better than before this CL. The windows/386 speed is not too important; the changes just keep the two architectures similar. Change-Id: If69b94970c8a1a57910a371ee91e0d4e82e46c5d Reviewed-on: https://go-review.googlesource.com/36428 Run-TryBot: Russ Cox <rsc@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-02-03 17:26:13 -07:00
// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Declarations for operating systems implementing time.now directly in assembly.
// Those systems are also expected to have nanotime subtract startNano,
// so that time.now and nanotime return the same monotonic clock readings.
runtime: implement time.now using libc Change-Id: Ibdd9202d9711ea8aab2446c9950ddb8e1f6bf4e0 Reviewed-on: https://go-review.googlesource.com/114799 Run-TryBot: Keith Randall <khr@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
2018-05-26 10:58:26 -06:00
// +build windows
time: optimize Now on darwin, windows Fetch both monotonic and wall time together when possible. Avoids skew and is cheaper. Also shave a few ns off in conversion in package time. Compared to current implementation (after monotonic changes): name old time/op new time/op delta Now 19.6ns ± 1% 9.7ns ± 1% -50.63% (p=0.000 n=41+49) darwin/amd64 Now 23.5ns ± 4% 10.6ns ± 5% -54.61% (p=0.000 n=30+28) windows/amd64 Now 54.5ns ± 5% 29.8ns ± 9% -45.40% (p=0.000 n=27+29) windows/386 More importantly, compared to Go 1.8: name old time/op new time/op delta Now 9.5ns ± 1% 9.7ns ± 1% +1.94% (p=0.000 n=41+49) darwin/amd64 Now 12.9ns ± 5% 10.6ns ± 5% -17.73% (p=0.000 n=30+28) windows/amd64 Now 15.3ns ± 5% 29.8ns ± 9% +94.36% (p=0.000 n=30+29) windows/386 This brings time.Now back in line with Go 1.8 on darwin/amd64 and windows/amd64. It's not obvious why windows/386 is still noticeably worse than Go 1.8, but it's better than before this CL. The windows/386 speed is not too important; the changes just keep the two architectures similar. Change-Id: If69b94970c8a1a57910a371ee91e0d4e82e46c5d Reviewed-on: https://go-review.googlesource.com/36428 Run-TryBot: Russ Cox <rsc@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-02-03 17:26:13 -07:00
package runtime
import _ "unsafe"
//go:linkname time_now time.now
func time_now() (sec int64, nsec int32, mono int64)
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