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 ( 8 "runtime/internal/atomic" 9 "unsafe" 10 ) 11 12 // GOMAXPROCS sets the maximum number of CPUs that can be executing 13 // simultaneously and returns the previous setting. If n < 1, it does not 14 // change the current setting. 15 // The number of logical CPUs on the local machine can be queried with NumCPU. 16 // This call will go away when the scheduler improves. 17 func GOMAXPROCS(n int) int { 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 // 36 // The set of available CPUs is checked by querying the operating system 37 // at process startup. Changes to operating system CPU allocation after 38 // process startup are not reflected. 39 func NumCPU() int { 40 return int(ncpu) 41 } 42 43 // NumCgoCall returns the number of cgo calls made by the current process. 44 func NumCgoCall() int64 { 45 var n int64 46 for mp := (*m)(atomic.Loadp(unsafe.Pointer(&allm))); mp != nil; mp = mp.alllink { 47 n += int64(mp.ncgocall) 48 } 49 return n 50 } 51 52 // NumGoroutine returns the number of goroutines that currently exist. 53 func NumGoroutine() int { 54 return int(gcount()) 55 } 56
