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      1 // Copyright 2013 The Go Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style
      3 // license that can be found in the LICENSE file.
      4 
      5 // The file contains tests that cannot run under race detector for some reason.
      6 // +build !race
      7 
      8 package runtime_test
      9 
     10 import (
     11 	"runtime"
     12 	"testing"
     13 )
     14 
     15 // Syscall tests split stack between Entersyscall and Exitsyscall under race detector.
     16 func BenchmarkSyscall(b *testing.B) {
     17 	benchmarkSyscall(b, 0, 1)
     18 }
     19 
     20 func BenchmarkSyscallWork(b *testing.B) {
     21 	benchmarkSyscall(b, 100, 1)
     22 }
     23 
     24 func BenchmarkSyscallExcess(b *testing.B) {
     25 	benchmarkSyscall(b, 0, 4)
     26 }
     27 
     28 func BenchmarkSyscallExcessWork(b *testing.B) {
     29 	benchmarkSyscall(b, 100, 4)
     30 }
     31 
     32 func benchmarkSyscall(b *testing.B, work, excess int) {
     33 	b.SetParallelism(excess)
     34 	b.RunParallel(func(pb *testing.PB) {
     35 		foo := 42
     36 		for pb.Next() {
     37 			runtime.Entersyscall(0)
     38 			for i := 0; i < work; i++ {
     39 				foo *= 2
     40 				foo /= 2
     41 			}
     42 			runtime.Exitsyscall(0)
     43 		}
     44 		_ = foo
     45 	})
     46 }
     47