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// Copyright 2009 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.
package runtime
import "unsafe"
// Note: the MemStats struct should be kept in sync with
// struct MStats in malloc.h
// A MemStats records statistics about the memory allocator.
type MemStats struct {
// General statistics.
Alloc uint64 // bytes allocated and still in use
TotalAlloc uint64 // bytes allocated (even if freed)
Sys uint64 // bytes obtained from system (sum of XxxSys below)
Lookups uint64 // number of pointer lookups
Mallocs uint64 // number of mallocs
Frees uint64 // number of frees
// Main allocation heap statistics.
HeapAlloc uint64 // bytes allocated and still in use
HeapSys uint64 // bytes obtained from system
HeapIdle uint64 // bytes in idle spans
HeapInuse uint64 // bytes in non-idle span
HeapReleased uint64 // bytes released to the OS
HeapObjects uint64 // total number of allocated objects
// Low-level fixed-size structure allocator statistics.
// Inuse is bytes used now.
// Sys is bytes obtained from system.
StackInuse uint64 // bytes used by stack allocator
StackSys uint64
MSpanInuse uint64 // mspan structures
MSpanSys uint64
MCacheInuse uint64 // mcache structures
MCacheSys uint64
BuckHashSys uint64 // profiling bucket hash table
GCSys uint64 // GC metadata
OtherSys uint64 // other system allocations
// Garbage collector statistics.
NextGC uint64 // next collection will happen when HeapAlloc ≥ this amount
LastGC uint64 // end time of last collection (nanoseconds since 1970)
PauseTotalNs uint64
PauseNs [256]uint64 // circular buffer of recent GC pause durations, most recent at [(NumGC+255)%256]
PauseEnd [256]uint64 // circular buffer of recent GC pause end times
NumGC uint32
EnableGC bool
DebugGC bool
// Per-size allocation statistics.
// 61 is NumSizeClasses in the C code.
BySize [61]struct {
Size uint32
Mallocs uint64
Frees uint64
}
}
// Size of the trailing by_size array differs between Go and C,
// and all data after by_size is local to runtime, not exported.
// NumSizeClasses was changed, but we can not change Go struct because of backward compatibility.
// sizeof_C_MStats is what C thinks about size of Go struct.
var sizeof_C_MStats = unsafe.Offsetof(memstats.by_size) + 61*unsafe.Sizeof(memstats.by_size[0])
func init() {
var memStats MemStats
if sizeof_C_MStats != unsafe.Sizeof(memStats) {
println(sizeof_C_MStats, unsafe.Sizeof(memStats))
gothrow("MStats vs MemStatsType size mismatch")
}
}
// ReadMemStats populates m with memory allocator statistics.
func ReadMemStats(m *MemStats) {
// Have to acquire worldsema to stop the world,
// because stoptheworld can only be used by
// one goroutine at a time, and there might be
// a pending garbage collection already calling it.
semacquire(&worldsema, false)
gp := getg()
gp.m.gcing = 1
systemstack(stoptheworld)
systemstack(func() {
readmemstats_m(m)
})
gp.m.gcing = 0
gp.m.locks++
semrelease(&worldsema)
systemstack(starttheworld)
gp.m.locks--
}
// Implementation of runtime/debug.WriteHeapDump
func writeHeapDump(fd uintptr) {
semacquire(&worldsema, false)
gp := getg()
gp.m.gcing = 1
systemstack(stoptheworld)
systemstack(func() {
writeheapdump_m(fd)
})
gp.m.gcing = 0
gp.m.locks++
semrelease(&worldsema)
systemstack(starttheworld)
gp.m.locks--
}
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