57 lines
1.5 KiB
Go
57 lines
1.5 KiB
Go
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// Copyright 2018 Google Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package time
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import (
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"syscall"
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"unsafe"
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)
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// syscallTSCReferenceClocks is the standard referenceClocks, collecting
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// samples using CLOCK_GETTIME and RDTSC.
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type syscallTSCReferenceClocks struct {
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tscCycleClock
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}
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// Sample implements sampler.Sample.
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func (syscallTSCReferenceClocks) Sample(c ClockID) (sample, error) {
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var s sample
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s.before = Rdtsc()
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// Don't call clockGettime to avoid a call which may call morestack.
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var ts syscall.Timespec
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_, _, e := syscall.RawSyscall(syscall.SYS_CLOCK_GETTIME, uintptr(c), uintptr(unsafe.Pointer(&ts)), 0)
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if e != 0 {
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return sample{}, e
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}
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s.after = Rdtsc()
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s.ref = ReferenceNS(ts.Nano())
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return s, nil
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}
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// clockGettime calls SYS_CLOCK_GETTIME, returning time in nanoseconds.
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func clockGettime(c ClockID) (ReferenceNS, error) {
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var ts syscall.Timespec
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_, _, e := syscall.RawSyscall(syscall.SYS_CLOCK_GETTIME, uintptr(c), uintptr(unsafe.Pointer(&ts)), 0)
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if e != 0 {
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return 0, e
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}
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return ReferenceNS(ts.Nano()), nil
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}
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