github.com/c0deoo1/golang1.5@v0.0.0-20220525150107-c87c805d4593/src/runtime/runtime.go (about)

     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" // for go:linkname
     8  
     9  //go:generate go run wincallback.go
    10  //go:generate go run mkduff.go
    11  
    12  var ticks struct {
    13  	lock mutex
    14  	pad  uint32 // ensure 8-byte alignment of val on 386
    15  	val  uint64
    16  }
    17  
    18  var tls0 [8]uintptr // available storage for m0's TLS; not necessarily used; opaque to GC
    19  
    20  // Note: Called by runtime/pprof in addition to runtime code.
    21  func tickspersecond() int64 {
    22  	r := int64(atomicload64(&ticks.val))
    23  	if r != 0 {
    24  		return r
    25  	}
    26  	lock(&ticks.lock)
    27  	r = int64(ticks.val)
    28  	if r == 0 {
    29  		t0 := nanotime()
    30  		c0 := cputicks()
    31  		usleep(100 * 1000)
    32  		t1 := nanotime()
    33  		c1 := cputicks()
    34  		if t1 == t0 {
    35  			t1++
    36  		}
    37  		r = (c1 - c0) * 1000 * 1000 * 1000 / (t1 - t0)
    38  		if r == 0 {
    39  			r++
    40  		}
    41  		atomicstore64(&ticks.val, uint64(r))
    42  	}
    43  	unlock(&ticks.lock)
    44  	return r
    45  }
    46  // 提供给os包来访问  os.runtime_args
    47  // 提供给syscall包来访问 syscall.runtime_envs
    48  var envs []string
    49  var argslice []string
    50  
    51  //go:linkname syscall_runtime_envs syscall.runtime_envs
    52  func syscall_runtime_envs() []string { return append([]string{}, envs...) }
    53  
    54  //go:linkname os_runtime_args os.runtime_args
    55  func os_runtime_args() []string { return append([]string{}, argslice...) }