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// Copyright 2013 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.
// The file contains tests that can not run under race detector for some reason.
// +build !race
package runtime_test
import (
"runtime"
"sync/atomic"
"testing"
)
// Syscall tests split stack between Entersyscall and Exitsyscall under race detector.
func BenchmarkSyscall(b *testing.B) {
benchmarkSyscall(b, 0, 1)
}
func BenchmarkSyscallWork(b *testing.B) {
benchmarkSyscall(b, 100, 1)
}
func BenchmarkSyscallExcess(b *testing.B) {
benchmarkSyscall(b, 0, 4)
}
func BenchmarkSyscallExcessWork(b *testing.B) {
benchmarkSyscall(b, 100, 4)
}
func benchmarkSyscall(b *testing.B, work, excess int) {
const CallsPerSched = 1000
procs := runtime.GOMAXPROCS(-1) * excess
N := int32(b.N / CallsPerSched)
c := make(chan bool, procs)
for p := 0; p < procs; p++ {
go func() {
foo := 42
for atomic.AddInt32(&N, -1) >= 0 {
runtime.Gosched()
for g := 0; g < CallsPerSched; g++ {
runtime.Entersyscall()
for i := 0; i < work; i++ {
foo *= 2
foo /= 2
}
runtime.Exitsyscall()
}
}
c <- foo == 42
}()
}
for p := 0; p < procs; p++ {
<-c
}
}
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