1 // Copyright 2009 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 package runtime 6 7 import "unsafe" 8 9 // GOMAXPROCS sets the maximum number of CPUs that can be executing 10 // simultaneously and returns the previous setting. If n < 1, it does not 11 // change the current setting. 12 // The number of logical CPUs on the local machine can be queried with NumCPU. 13 // This call will go away when the scheduler improves. 14 func GOMAXPROCS(n int) int { 15 if n > _MaxGomaxprocs { 16 n = _MaxGomaxprocs 17 } 18 lock(&sched.lock) 19 ret := int(gomaxprocs) 20 unlock(&sched.lock) 21 if n <= 0 || n == ret { 22 return ret 23 } 24 25 stopTheWorld("GOMAXPROCS") 26 27 // newprocs will be processed by startTheWorld 28 newprocs = int32(n) 29 30 startTheWorld() 31 return ret 32 } 33 34 // NumCPU returns the number of logical CPUs usable by the current process. 35 func NumCPU() int { 36 return int(ncpu) 37 } 38 39 // NumCgoCall returns the number of cgo calls made by the current process. 40 func NumCgoCall() int64 { 41 var n int64 42 for mp := (*m)(atomicloadp(unsafe.Pointer(&allm))); mp != nil; mp = mp.alllink { 43 n += int64(mp.ncgocall) 44 } 45 return n 46 } 47 48 // NumGoroutine returns the number of goroutines that currently exist. 49 func NumGoroutine() int { 50 return int(gcount()) 51 } 52
