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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.
// Page heap.
//
// See malloc.go for overview.
package runtime
import "unsafe"
// Main malloc heap.
// The heap itself is the "free[]" and "large" arrays,
// but all the other global data is here too.
type mheap struct {
lock mutex
free [_MaxMHeapList]mspan // free lists of given length
freelarge mspan // free lists length >= _MaxMHeapList
busy [_MaxMHeapList]mspan // busy lists of large objects of given length
busylarge mspan // busy lists of large objects length >= _MaxMHeapList
allspans **mspan // all spans out there
gcspans **mspan // copy of allspans referenced by gc marker or sweeper
nspan uint32
sweepgen uint32 // sweep generation, see comment in mspan
sweepdone uint32 // all spans are swept
// span lookup
spans **mspan
spans_mapped uintptr
// range of addresses we might see in the heap
bitmap uintptr
bitmap_mapped uintptr
arena_start uintptr
arena_used uintptr
arena_end uintptr
arena_reserved bool
// write barrier shadow heap.
// 64-bit systems only, enabled by GODEBUG=wbshadow=1.
// See also shadow_data, data_start, data_end fields on moduledata in
// symtab.go.
shadow_enabled bool // shadow should be updated and checked
shadow_reserved bool // shadow memory is reserved
shadow_heap uintptr // heap-addr + shadow_heap = shadow heap addr
// central free lists for small size classes.
// the padding makes sure that the MCentrals are
// spaced CacheLineSize bytes apart, so that each MCentral.lock
// gets its own cache line.
central [_NumSizeClasses]struct {
mcentral mcentral
pad [_CacheLineSize]byte
}
spanalloc fixalloc // allocator for span*
cachealloc fixalloc // allocator for mcache*
specialfinalizeralloc fixalloc // allocator for specialfinalizer*
specialprofilealloc fixalloc // allocator for specialprofile*
speciallock mutex // lock for sepcial record allocators.
// Proportional sweep
pagesSwept uint64 // pages swept this cycle; updated atomically
sweepPagesPerByte float64 // proportional sweep ratio; written with lock, read without
// Malloc stats.
largefree uint64 // bytes freed for large objects (>maxsmallsize)
nlargefree uint64 // number of frees for large objects (>maxsmallsize)
nsmallfree [_NumSizeClasses]uint64 // number of frees for small objects (<=maxsmallsize)
}
var mheap_ mheap
// An MSpan is a run of pages.
//
// When a MSpan is in the heap free list, state == MSpanFree
// and heapmap(s->start) == span, heapmap(s->start+s->npages-1) == span.
//
// When a MSpan is allocated, state == MSpanInUse or MSpanStack
// and heapmap(i) == span for all s->start <= i < s->start+s->npages.
// Every MSpan is in one doubly-linked list,
// either one of the MHeap's free lists or one of the
// MCentral's span lists. We use empty MSpan structures as list heads.
const (
_MSpanInUse = iota // allocated for garbage collected heap
_MSpanStack // allocated for use by stack allocator
_MSpanFree
_MSpanListHead
_MSpanDead
)
type mspan struct {
next *mspan // in a span linked list
prev *mspan // in a span linked list
start pageID // starting page number
npages uintptr // number of pages in span
freelist gclinkptr // list of free objects
// sweep generation:
// if sweepgen == h->sweepgen - 2, the span needs sweeping
// if sweepgen == h->sweepgen - 1, the span is currently being swept
// if sweepgen == h->sweepgen, the span is swept and ready to use
// h->sweepgen is incremented by 2 after every GC
sweepgen uint32
divMul uint32 // for divide by elemsize - divMagic.mul
ref uint16 // capacity - number of objects in freelist
sizeclass uint8 // size class
incache bool // being used by an mcache
state uint8 // mspaninuse etc
needzero uint8 // needs to be zeroed before allocation
divShift uint8 // for divide by elemsize - divMagic.shift
divShift2 uint8 // for divide by elemsize - divMagic.shift2
elemsize uintptr // computed from sizeclass or from npages
unusedsince int64 // first time spotted by gc in mspanfree state
npreleased uintptr // number of pages released to the os
limit uintptr // end of data in span
speciallock mutex // guards specials list
specials *special // linked list of special records sorted by offset.
baseMask uintptr // if non-0, elemsize is a power of 2, & this will get object allocation base
}
func (s *mspan) base() uintptr {
return uintptr(s.start << _PageShift)
}
func (s *mspan) layout() (size, n, total uintptr) {
total = s.npages << _PageShift
size = s.elemsize
if size > 0 {
n = total / size
}
return
}
var h_allspans []*mspan // TODO: make this h.allspans once mheap can be defined in Go
// h_spans is a lookup table to map virtual address page IDs to *mspan.
// For allocated spans, their pages map to the span itself.
// For free spans, only the lowest and highest pages map to the span itself. Internal
// pages map to an arbitrary span.
// For pages that have never been allocated, h_spans entries are nil.
var h_spans []*mspan // TODO: make this h.spans once mheap can be defined in Go
func recordspan(vh unsafe.Pointer, p unsafe.Pointer) {
h := (*mheap)(vh)
s := (*mspan)(p)
if len(h_allspans) >= cap(h_allspans) {
n := 64 * 1024 / ptrSize
if n < cap(h_allspans)*3/2 {
n = cap(h_allspans) * 3 / 2
}
var new []*mspan
sp := (*slice)(unsafe.Pointer(&new))
sp.array = sysAlloc(uintptr(n)*ptrSize, &memstats.other_sys)
if sp.array == nil {
throw("runtime: cannot allocate memory")
}
sp.len = len(h_allspans)
sp.cap = n
if len(h_allspans) > 0 {
copy(new, h_allspans)
// Don't free the old array if it's referenced by sweep.
// See the comment in mgc.go.
if h.allspans != mheap_.gcspans {
sysFree(unsafe.Pointer(h.allspans), uintptr(cap(h_allspans))*ptrSize, &memstats.other_sys)
}
}
h_allspans = new
h.allspans = (**mspan)(unsafe.Pointer(sp.array))
}
h_allspans = append(h_allspans, s)
h.nspan = uint32(len(h_allspans))
}
// inheap reports whether b is a pointer into a (potentially dead) heap object.
// It returns false for pointers into stack spans.
//go:nowritebarrier
func inheap(b uintptr) bool {
if b == 0 || b < mheap_.arena_start || b >= mheap_.arena_used {
return false
}
// Not a beginning of a block, consult span table to find the block beginning.
k := b >> _PageShift
x := k
x -= mheap_.arena_start >> _PageShift
s := h_spans[x]
if s == nil || pageID(k) < s.start || b >= s.limit || s.state != mSpanInUse {
return false
}
return true
}
func mlookup(v uintptr, base *uintptr, size *uintptr, sp **mspan) int32 {
_g_ := getg()
_g_.m.mcache.local_nlookup++
if ptrSize == 4 && _g_.m.mcache.local_nlookup >= 1<<30 {
// purge cache stats to prevent overflow
lock(&mheap_.lock)
purgecachedstats(_g_.m.mcache)
unlock(&mheap_.lock)
}
s := mHeap_LookupMaybe(&mheap_, unsafe.Pointer(v))
if sp != nil {
*sp = s
}
if s == nil {
if base != nil {
*base = 0
}
if size != nil {
*size = 0
}
return 0
}
p := uintptr(s.start) << _PageShift
if s.sizeclass == 0 {
// Large object.
if base != nil {
*base = p
}
if size != nil {
*size = s.npages << _PageShift
}
return 1
}
n := s.elemsize
if base != nil {
i := (uintptr(v) - uintptr(p)) / n
*base = p + i*n
}
if size != nil {
*size = n
}
return 1
}
// Initialize the heap.
func mHeap_Init(h *mheap, spans_size uintptr) {
fixAlloc_Init(&h.spanalloc, unsafe.Sizeof(mspan{}), recordspan, unsafe.Pointer(h), &memstats.mspan_sys)
fixAlloc_Init(&h.cachealloc, unsafe.Sizeof(mcache{}), nil, nil, &memstats.mcache_sys)
fixAlloc_Init(&h.specialfinalizeralloc, unsafe.Sizeof(specialfinalizer{}), nil, nil, &memstats.other_sys)
fixAlloc_Init(&h.specialprofilealloc, unsafe.Sizeof(specialprofile{}), nil, nil, &memstats.other_sys)
// h->mapcache needs no init
for i := range h.free {
mSpanList_Init(&h.free[i])
mSpanList_Init(&h.busy[i])
}
mSpanList_Init(&h.freelarge)
mSpanList_Init(&h.busylarge)
for i := range h.central {
mCentral_Init(&h.central[i].mcentral, int32(i))
}
sp := (*slice)(unsafe.Pointer(&h_spans))
sp.array = unsafe.Pointer(h.spans)
sp.len = int(spans_size / ptrSize)
sp.cap = int(spans_size / ptrSize)
}
func mHeap_MapSpans(h *mheap) {
// Map spans array, PageSize at a time.
n := uintptr(unsafe.Pointer(h.arena_used))
n -= uintptr(unsafe.Pointer(h.arena_start))
n = n / _PageSize * ptrSize
n = round(n, _PhysPageSize)
if h.spans_mapped >= n {
return
}
sysMap(add(unsafe.Pointer(h.spans), h.spans_mapped), n-h.spans_mapped, h.arena_reserved, &memstats.other_sys)
h.spans_mapped = n
}
// Sweeps spans in list until reclaims at least npages into heap.
// Returns the actual number of pages reclaimed.
func mHeap_ReclaimList(h *mheap, list *mspan, npages uintptr) uintptr {
n := uintptr(0)
sg := mheap_.sweepgen
retry:
for s := list.next; s != list; s = s.next {
if s.sweepgen == sg-2 && cas(&s.sweepgen, sg-2, sg-1) {
mSpanList_Remove(s)
// swept spans are at the end of the list
mSpanList_InsertBack(list, s)
unlock(&h.lock)
snpages := s.npages
if mSpan_Sweep(s, false) {
n += snpages
}
lock(&h.lock)
if n >= npages {
return n
}
// the span could have been moved elsewhere
goto retry
}
if s.sweepgen == sg-1 {
// the span is being sweept by background sweeper, skip
continue
}
// already swept empty span,
// all subsequent ones must also be either swept or in process of sweeping
break
}
return n
}
// Sweeps and reclaims at least npage pages into heap.
// Called before allocating npage pages.
func mHeap_Reclaim(h *mheap, npage uintptr) {
// First try to sweep busy spans with large objects of size >= npage,
// this has good chances of reclaiming the necessary space.
for i := int(npage); i < len(h.busy); i++ {
if mHeap_ReclaimList(h, &h.busy[i], npage) != 0 {
return // Bingo!
}
}
// Then -- even larger objects.
if mHeap_ReclaimList(h, &h.busylarge, npage) != 0 {
return // Bingo!
}
// Now try smaller objects.
// One such object is not enough, so we need to reclaim several of them.
reclaimed := uintptr(0)
for i := 0; i < int(npage) && i < len(h.busy); i++ {
reclaimed += mHeap_ReclaimList(h, &h.busy[i], npage-reclaimed)
if reclaimed >= npage {
return
}
}
// Now sweep everything that is not yet swept.
unlock(&h.lock)
for {
n := sweepone()
if n == ^uintptr(0) { // all spans are swept
break
}
reclaimed += n
if reclaimed >= npage {
break
}
}
lock(&h.lock)
}
// Allocate a new span of npage pages from the heap for GC'd memory
// and record its size class in the HeapMap and HeapMapCache.
func mHeap_Alloc_m(h *mheap, npage uintptr, sizeclass int32, large bool) *mspan {
_g_ := getg()
if _g_ != _g_.m.g0 {
throw("_mheap_alloc not on g0 stack")
}
lock(&h.lock)
// To prevent excessive heap growth, before allocating n pages
// we need to sweep and reclaim at least n pages.
if h.sweepdone == 0 {
// TODO(austin): This tends to sweep a large number of
// spans in order to find a few completely free spans
// (for example, in the garbage benchmark, this sweeps
// ~30x the number of pages its trying to allocate).
// If GC kept a bit for whether there were any marks
// in a span, we could release these free spans
// at the end of GC and eliminate this entirely.
mHeap_Reclaim(h, npage)
}
// transfer stats from cache to global
memstats.heap_live += uint64(_g_.m.mcache.local_cachealloc)
_g_.m.mcache.local_cachealloc = 0
memstats.tinyallocs += uint64(_g_.m.mcache.local_tinyallocs)
_g_.m.mcache.local_tinyallocs = 0
s := mHeap_AllocSpanLocked(h, npage)
if s != nil {
// Record span info, because gc needs to be
// able to map interior pointer to containing span.
atomicstore(&s.sweepgen, h.sweepgen)
s.state = _MSpanInUse
s.freelist = 0
s.ref = 0
s.sizeclass = uint8(sizeclass)
if sizeclass == 0 {
s.elemsize = s.npages << _PageShift
s.divShift = 0
s.divMul = 0
s.divShift2 = 0
s.baseMask = 0
} else {
s.elemsize = uintptr(class_to_size[sizeclass])
m := &class_to_divmagic[sizeclass]
s.divShift = m.shift
s.divMul = m.mul
s.divShift2 = m.shift2
s.baseMask = m.baseMask
}
// update stats, sweep lists
if large {
memstats.heap_objects++
memstats.heap_live += uint64(npage << _PageShift)
// Swept spans are at the end of lists.
if s.npages < uintptr(len(h.free)) {
mSpanList_InsertBack(&h.busy[s.npages], s)
} else {
mSpanList_InsertBack(&h.busylarge, s)
}
}
}
if trace.enabled {
traceHeapAlloc()
}
unlock(&h.lock)
return s
}
func mHeap_Alloc(h *mheap, npage uintptr, sizeclass int32, large bool, needzero bool) *mspan {
// Don't do any operations that lock the heap on the G stack.
// It might trigger stack growth, and the stack growth code needs
// to be able to allocate heap.
var s *mspan
systemstack(func() {
s = mHeap_Alloc_m(h, npage, sizeclass, large)
})
if s != nil {
if needzero && s.needzero != 0 {
memclr(unsafe.Pointer(s.start<<_PageShift), s.npages<<_PageShift)
}
s.needzero = 0
}
return s
}
func mHeap_AllocStack(h *mheap, npage uintptr) *mspan {
_g_ := getg()
if _g_ != _g_.m.g0 {
throw("mheap_allocstack not on g0 stack")
}
lock(&h.lock)
s := mHeap_AllocSpanLocked(h, npage)
if s != nil {
s.state = _MSpanStack
s.freelist = 0
s.ref = 0
memstats.stacks_inuse += uint64(s.npages << _PageShift)
}
unlock(&h.lock)
return s
}
// Allocates a span of the given size. h must be locked.
// The returned span has been removed from the
// free list, but its state is still MSpanFree.
func mHeap_AllocSpanLocked(h *mheap, npage uintptr) *mspan {
var s *mspan
// Try in fixed-size lists up to max.
for i := int(npage); i < len(h.free); i++ {
if !mSpanList_IsEmpty(&h.free[i]) {
s = h.free[i].next
goto HaveSpan
}
}
// Best fit in list of large spans.
s = mHeap_AllocLarge(h, npage)
if s == nil {
if !mHeap_Grow(h, npage) {
return nil
}
s = mHeap_AllocLarge(h, npage)
if s == nil {
return nil
}
}
HaveSpan:
// Mark span in use.
if s.state != _MSpanFree {
throw("MHeap_AllocLocked - MSpan not free")
}
if s.npages < npage {
throw("MHeap_AllocLocked - bad npages")
}
mSpanList_Remove(s)
if s.next != nil || s.prev != nil {
throw("still in list")
}
if s.npreleased > 0 {
sysUsed((unsafe.Pointer)(s.start<<_PageShift), s.npages<<_PageShift)
memstats.heap_released -= uint64(s.npreleased << _PageShift)
s.npreleased = 0
}
if s.npages > npage {
// Trim extra and put it back in the heap.
t := (*mspan)(fixAlloc_Alloc(&h.spanalloc))
mSpan_Init(t, s.start+pageID(npage), s.npages-npage)
s.npages = npage
p := uintptr(t.start)
p -= (uintptr(unsafe.Pointer(h.arena_start)) >> _PageShift)
if p > 0 {
h_spans[p-1] = s
}
h_spans[p] = t
h_spans[p+t.npages-1] = t
t.needzero = s.needzero
s.state = _MSpanStack // prevent coalescing with s
t.state = _MSpanStack
mHeap_FreeSpanLocked(h, t, false, false, s.unusedsince)
s.state = _MSpanFree
}
s.unusedsince = 0
p := uintptr(s.start)
p -= (uintptr(unsafe.Pointer(h.arena_start)) >> _PageShift)
for n := uintptr(0); n < npage; n++ {
h_spans[p+n] = s
}
memstats.heap_inuse += uint64(npage << _PageShift)
memstats.heap_idle -= uint64(npage << _PageShift)
//println("spanalloc", hex(s.start<<_PageShift))
if s.next != nil || s.prev != nil {
throw("still in list")
}
return s
}
// Allocate a span of exactly npage pages from the list of large spans.
func mHeap_AllocLarge(h *mheap, npage uintptr) *mspan {
return bestFit(&h.freelarge, npage, nil)
}
// Search list for smallest span with >= npage pages.
// If there are multiple smallest spans, take the one
// with the earliest starting address.
func bestFit(list *mspan, npage uintptr, best *mspan) *mspan {
for s := list.next; s != list; s = s.next {
if s.npages < npage {
continue
}
if best == nil || s.npages < best.npages || (s.npages == best.npages && s.start < best.start) {
best = s
}
}
return best
}
// Try to add at least npage pages of memory to the heap,
// returning whether it worked.
func mHeap_Grow(h *mheap, npage uintptr) bool {
// Ask for a big chunk, to reduce the number of mappings
// the operating system needs to track; also amortizes
// the overhead of an operating system mapping.
// Allocate a multiple of 64kB.
npage = round(npage, (64<<10)/_PageSize)
ask := npage << _PageShift
if ask < _HeapAllocChunk {
ask = _HeapAllocChunk
}
v := mHeap_SysAlloc(h, ask)
if v == nil {
if ask > npage<<_PageShift {
ask = npage << _PageShift
v = mHeap_SysAlloc(h, ask)
}
if v == nil {
print("runtime: out of memory: cannot allocate ", ask, "-byte block (", memstats.heap_sys, " in use)\n")
return false
}
}
// Create a fake "in use" span and free it, so that the
// right coalescing happens.
s := (*mspan)(fixAlloc_Alloc(&h.spanalloc))
mSpan_Init(s, pageID(uintptr(v)>>_PageShift), ask>>_PageShift)
p := uintptr(s.start)
p -= (uintptr(unsafe.Pointer(h.arena_start)) >> _PageShift)
for i := p; i < p+s.npages; i++ {
h_spans[i] = s
}
atomicstore(&s.sweepgen, h.sweepgen)
s.state = _MSpanInUse
mHeap_FreeSpanLocked(h, s, false, true, 0)
return true
}
// Look up the span at the given address.
// Address is guaranteed to be in map
// and is guaranteed to be start or end of span.
func mHeap_Lookup(h *mheap, v unsafe.Pointer) *mspan {
p := uintptr(v)
p -= uintptr(unsafe.Pointer(h.arena_start))
return h_spans[p>>_PageShift]
}
// Look up the span at the given address.
// Address is *not* guaranteed to be in map
// and may be anywhere in the span.
// Map entries for the middle of a span are only
// valid for allocated spans. Free spans may have
// other garbage in their middles, so we have to
// check for that.
func mHeap_LookupMaybe(h *mheap, v unsafe.Pointer) *mspan {
if uintptr(v) < uintptr(unsafe.Pointer(h.arena_start)) || uintptr(v) >= uintptr(unsafe.Pointer(h.arena_used)) {
return nil
}
p := uintptr(v) >> _PageShift
q := p
q -= uintptr(unsafe.Pointer(h.arena_start)) >> _PageShift
s := h_spans[q]
if s == nil || p < uintptr(s.start) || uintptr(v) >= uintptr(unsafe.Pointer(s.limit)) || s.state != _MSpanInUse {
return nil
}
return s
}
// Free the span back into the heap.
func mHeap_Free(h *mheap, s *mspan, acct int32) {
systemstack(func() {
mp := getg().m
lock(&h.lock)
memstats.heap_live += uint64(mp.mcache.local_cachealloc)
mp.mcache.local_cachealloc = 0
memstats.tinyallocs += uint64(mp.mcache.local_tinyallocs)
mp.mcache.local_tinyallocs = 0
if acct != 0 {
memstats.heap_objects--
}
mHeap_FreeSpanLocked(h, s, true, true, 0)
if trace.enabled {
traceHeapAlloc()
}
unlock(&h.lock)
})
}
func mHeap_FreeStack(h *mheap, s *mspan) {
_g_ := getg()
if _g_ != _g_.m.g0 {
throw("mheap_freestack not on g0 stack")
}
s.needzero = 1
lock(&h.lock)
memstats.stacks_inuse -= uint64(s.npages << _PageShift)
mHeap_FreeSpanLocked(h, s, true, true, 0)
unlock(&h.lock)
}
func mHeap_FreeSpanLocked(h *mheap, s *mspan, acctinuse, acctidle bool, unusedsince int64) {
switch s.state {
case _MSpanStack:
if s.ref != 0 {
throw("MHeap_FreeSpanLocked - invalid stack free")
}
case _MSpanInUse:
if s.ref != 0 || s.sweepgen != h.sweepgen {
print("MHeap_FreeSpanLocked - span ", s, " ptr ", hex(s.start<<_PageShift), " ref ", s.ref, " sweepgen ", s.sweepgen, "/", h.sweepgen, "\n")
throw("MHeap_FreeSpanLocked - invalid free")
}
default:
throw("MHeap_FreeSpanLocked - invalid span state")
}
if acctinuse {
memstats.heap_inuse -= uint64(s.npages << _PageShift)
}
if acctidle {
memstats.heap_idle += uint64(s.npages << _PageShift)
}
s.state = _MSpanFree
mSpanList_Remove(s)
// Stamp newly unused spans. The scavenger will use that
// info to potentially give back some pages to the OS.
s.unusedsince = unusedsince
if unusedsince == 0 {
s.unusedsince = nanotime()
}
s.npreleased = 0
// Coalesce with earlier, later spans.
p := uintptr(s.start)
p -= uintptr(unsafe.Pointer(h.arena_start)) >> _PageShift
if p > 0 {
t := h_spans[p-1]
if t != nil && t.state != _MSpanInUse && t.state != _MSpanStack {
s.start = t.start
s.npages += t.npages
s.npreleased = t.npreleased // absorb released pages
s.needzero |= t.needzero
p -= t.npages
h_spans[p] = s
mSpanList_Remove(t)
t.state = _MSpanDead
fixAlloc_Free(&h.spanalloc, (unsafe.Pointer)(t))
}
}
if (p+s.npages)*ptrSize < h.spans_mapped {
t := h_spans[p+s.npages]
if t != nil && t.state != _MSpanInUse && t.state != _MSpanStack {
s.npages += t.npages
s.npreleased += t.npreleased
s.needzero |= t.needzero
h_spans[p+s.npages-1] = s
mSpanList_Remove(t)
t.state = _MSpanDead
fixAlloc_Free(&h.spanalloc, (unsafe.Pointer)(t))
}
}
// Insert s into appropriate list.
if s.npages < uintptr(len(h.free)) {
mSpanList_Insert(&h.free[s.npages], s)
} else {
mSpanList_Insert(&h.freelarge, s)
}
}
func scavengelist(list *mspan, now, limit uint64) uintptr {
if _PhysPageSize > _PageSize {
// golang.org/issue/9993
// If the physical page size of the machine is larger than
// our logical heap page size the kernel may round up the
// amount to be freed to its page size and corrupt the heap
// pages surrounding the unused block.
return 0
}
if mSpanList_IsEmpty(list) {
return 0
}
var sumreleased uintptr
for s := list.next; s != list; s = s.next {
if (now-uint64(s.unusedsince)) > limit && s.npreleased != s.npages {
released := (s.npages - s.npreleased) << _PageShift
memstats.heap_released += uint64(released)
sumreleased += released
s.npreleased = s.npages
sysUnused((unsafe.Pointer)(s.start<<_PageShift), s.npages<<_PageShift)
}
}
return sumreleased
}
func mHeap_Scavenge(k int32, now, limit uint64) {
h := &mheap_
lock(&h.lock)
var sumreleased uintptr
for i := 0; i < len(h.free); i++ {
sumreleased += scavengelist(&h.free[i], now, limit)
}
sumreleased += scavengelist(&h.freelarge, now, limit)
unlock(&h.lock)
if debug.gctrace > 0 {
if sumreleased > 0 {
print("scvg", k, ": ", sumreleased>>20, " MB released\n")
}
// TODO(dvyukov): these stats are incorrect as we don't subtract stack usage from heap.
// But we can't call ReadMemStats on g0 holding locks.
print("scvg", k, ": inuse: ", memstats.heap_inuse>>20, ", idle: ", memstats.heap_idle>>20, ", sys: ", memstats.heap_sys>>20, ", released: ", memstats.heap_released>>20, ", consumed: ", (memstats.heap_sys-memstats.heap_released)>>20, " (MB)\n")
}
}
//go:linkname runtime_debug_freeOSMemory runtime/debug.freeOSMemory
func runtime_debug_freeOSMemory() {
startGC(gcForceBlockMode)
systemstack(func() { mHeap_Scavenge(-1, ^uint64(0), 0) })
}
// Initialize a new span with the given start and npages.
func mSpan_Init(span *mspan, start pageID, npages uintptr) {
span.next = nil
span.prev = nil
span.start = start
span.npages = npages
span.freelist = 0
span.ref = 0
span.sizeclass = 0
span.incache = false
span.elemsize = 0
span.state = _MSpanDead
span.unusedsince = 0
span.npreleased = 0
span.speciallock.key = 0
span.specials = nil
span.needzero = 0
}
// Initialize an empty doubly-linked list.
func mSpanList_Init(list *mspan) {
list.state = _MSpanListHead
list.next = list
list.prev = list
}
func mSpanList_Remove(span *mspan) {
if span.prev == nil && span.next == nil {
return
}
span.prev.next = span.next
span.next.prev = span.prev
span.prev = nil
span.next = nil
}
func mSpanList_IsEmpty(list *mspan) bool {
return list.next == list
}
func mSpanList_Insert(list *mspan, span *mspan) {
if span.next != nil || span.prev != nil {
println("failed MSpanList_Insert", span, span.next, span.prev)
throw("MSpanList_Insert")
}
span.next = list.next
span.prev = list
span.next.prev = span
span.prev.next = span
}
func mSpanList_InsertBack(list *mspan, span *mspan) {
if span.next != nil || span.prev != nil {
println("failed MSpanList_InsertBack", span, span.next, span.prev)
throw("MSpanList_InsertBack")
}
span.next = list
span.prev = list.prev
span.next.prev = span
span.prev.next = span
}
const (
_KindSpecialFinalizer = 1
_KindSpecialProfile = 2
// Note: The finalizer special must be first because if we're freeing
// an object, a finalizer special will cause the freeing operation
// to abort, and we want to keep the other special records around
// if that happens.
)
type special struct {
next *special // linked list in span
offset uint16 // span offset of object
kind byte // kind of special
}
// Adds the special record s to the list of special records for
// the object p. All fields of s should be filled in except for
// offset & next, which this routine will fill in.
// Returns true if the special was successfully added, false otherwise.
// (The add will fail only if a record with the same p and s->kind
// already exists.)
func addspecial(p unsafe.Pointer, s *special) bool {
span := mHeap_LookupMaybe(&mheap_, p)
if span == nil {
throw("addspecial on invalid pointer")
}
// Ensure that the span is swept.
// GC accesses specials list w/o locks. And it's just much safer.
mp := acquirem()
mSpan_EnsureSwept(span)
offset := uintptr(p) - uintptr(span.start<<_PageShift)
kind := s.kind
lock(&span.speciallock)
// Find splice point, check for existing record.
t := &span.specials
for {
x := *t
if x == nil {
break
}
if offset == uintptr(x.offset) && kind == x.kind {
unlock(&span.speciallock)
releasem(mp)
return false // already exists
}
if offset < uintptr(x.offset) || (offset == uintptr(x.offset) && kind < x.kind) {
break
}
t = &x.next
}
// Splice in record, fill in offset.
s.offset = uint16(offset)
s.next = *t
*t = s
unlock(&span.speciallock)
releasem(mp)
return true
}
// Removes the Special record of the given kind for the object p.
// Returns the record if the record existed, nil otherwise.
// The caller must FixAlloc_Free the result.
func removespecial(p unsafe.Pointer, kind uint8) *special {
span := mHeap_LookupMaybe(&mheap_, p)
if span == nil {
throw("removespecial on invalid pointer")
}
// Ensure that the span is swept.
// GC accesses specials list w/o locks. And it's just much safer.
mp := acquirem()
mSpan_EnsureSwept(span)
offset := uintptr(p) - uintptr(span.start<<_PageShift)
lock(&span.speciallock)
t := &span.specials
for {
s := *t
if s == nil {
break
}
// This function is used for finalizers only, so we don't check for
// "interior" specials (p must be exactly equal to s->offset).
if offset == uintptr(s.offset) && kind == s.kind {
*t = s.next
unlock(&span.speciallock)
releasem(mp)
return s
}
t = &s.next
}
unlock(&span.speciallock)
releasem(mp)
return nil
}
// The described object has a finalizer set for it.
type specialfinalizer struct {
special special
fn *funcval
nret uintptr
fint *_type
ot *ptrtype
}
// Adds a finalizer to the object p. Returns true if it succeeded.
func addfinalizer(p unsafe.Pointer, f *funcval, nret uintptr, fint *_type, ot *ptrtype) bool {
lock(&mheap_.speciallock)
s := (*specialfinalizer)(fixAlloc_Alloc(&mheap_.specialfinalizeralloc))
unlock(&mheap_.speciallock)
s.special.kind = _KindSpecialFinalizer
s.fn = f
s.nret = nret
s.fint = fint
s.ot = ot
if addspecial(p, &s.special) {
return true
}
// There was an old finalizer
lock(&mheap_.speciallock)
fixAlloc_Free(&mheap_.specialfinalizeralloc, (unsafe.Pointer)(s))
unlock(&mheap_.speciallock)
return false
}
// Removes the finalizer (if any) from the object p.
func removefinalizer(p unsafe.Pointer) {
s := (*specialfinalizer)(unsafe.Pointer(removespecial(p, _KindSpecialFinalizer)))
if s == nil {
return // there wasn't a finalizer to remove
}
lock(&mheap_.speciallock)
fixAlloc_Free(&mheap_.specialfinalizeralloc, (unsafe.Pointer)(s))
unlock(&mheap_.speciallock)
}
// The described object is being heap profiled.
type specialprofile struct {
special special
b *bucket
}
// Set the heap profile bucket associated with addr to b.
func setprofilebucket(p unsafe.Pointer, b *bucket) {
lock(&mheap_.speciallock)
s := (*specialprofile)(fixAlloc_Alloc(&mheap_.specialprofilealloc))
unlock(&mheap_.speciallock)
s.special.kind = _KindSpecialProfile
s.b = b
if !addspecial(p, &s.special) {
throw("setprofilebucket: profile already set")
}
}
// Do whatever cleanup needs to be done to deallocate s. It has
// already been unlinked from the MSpan specials list.
// Returns true if we should keep working on deallocating p.
func freespecial(s *special, p unsafe.Pointer, size uintptr, freed bool) bool {
switch s.kind {
case _KindSpecialFinalizer:
sf := (*specialfinalizer)(unsafe.Pointer(s))
queuefinalizer(p, sf.fn, sf.nret, sf.fint, sf.ot)
lock(&mheap_.speciallock)
fixAlloc_Free(&mheap_.specialfinalizeralloc, (unsafe.Pointer)(sf))
unlock(&mheap_.speciallock)
return false // don't free p until finalizer is done
case _KindSpecialProfile:
sp := (*specialprofile)(unsafe.Pointer(s))
mProf_Free(sp.b, size, freed)
lock(&mheap_.speciallock)
fixAlloc_Free(&mheap_.specialprofilealloc, (unsafe.Pointer)(sp))
unlock(&mheap_.speciallock)
return true
default:
throw("bad special kind")
panic("not reached")
}
}