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runtime: consolidate h_allspans and mheap_.allspans

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These are two ways to refer to the allspans array that hark back to
when the runtime was split between C and Go. Clean this up by making
mheap_.allspans a slice and eliminating h_allspans.

Change-Id: Ic9360d040cf3eb590b5dfbab0b82e8ace8525610
Reviewed-on: https://go-review.googlesource.com/30530
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>
This commit is contained in:
Austin Clements 2016-10-04 15:51:31 -04:00
parent adda7ad295
commit 4d6207790b
5 changed files with 42 additions and 31 deletions
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56
src/runtime/mheap.go
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@ -33,15 +33,29 @@ type mheap struct {
freelarge mSpanList // free lists length >= _MaxMHeapList
busy [_MaxMHeapList]mSpanList // busy lists of large objects of given length
busylarge mSpanList // 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
sweepgen uint32 // sweep generation, see comment in mspan
sweepdone uint32 // all spans are swept
// allspans is a slice of all mspans ever created. Each mspan
// appears exactly once.
//
// The memory for allspans is manually managed and can be
// reallocated and move as the heap grows.
//
// In general, allspans is protected by mheap_.lock, which
// prevents concurrent access as well as freeing the backing
// store. Accesses during STW might not hold the lock, but
// must ensure that allocation cannot happen around the
// access (since that may free the backing store).
allspans []*mspan // all spans out there
nspan uint32
// span lookup
spans **mspan
spans_mapped uintptr
_ uint32 // align uint64 fields on 32-bit for atomics
// Proportional sweep
pagesInUse uint64 // pages of spans in stats _MSpanInUse; R/W with mheap.lock
spanBytesAlloc uint64 // bytes of spans allocated this cycle; updated atomically
@ -233,8 +247,6 @@ func (s *mspan) layout() (size, n, total uintptr) {
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
@ -245,10 +257,10 @@ 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) {
if len(h.allspans) >= cap(h.allspans) {
n := 64 * 1024 / sys.PtrSize
if n < cap(h_allspans)*3/2 {
n = cap(h_allspans) * 3 / 2
if n < cap(h.allspans)*3/2 {
n = cap(h.allspans) * 3 / 2
}
var new []*mspan
sp := (*slice)(unsafe.Pointer(&new))
@ -256,21 +268,21 @@ func recordspan(vh unsafe.Pointer, p unsafe.Pointer) {
if sp.array == nil {
throw("runtime: cannot allocate memory")
}
sp.len = len(h_allspans)
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))*sys.PtrSize, &memstats.other_sys)
}
if len(h.allspans) > 0 {
copy(new, h.allspans)
}
oldAllspans := h.allspans
h.allspans = new
// Don't free the old array if it's referenced by sweep.
// See the comment in mgc.go.
if len(oldAllspans) != 0 && &oldAllspans[0] != &work.spans[0] {
sysFree(unsafe.Pointer(&oldAllspans[0]), uintptr(cap(oldAllspans))*unsafe.Sizeof(oldAllspans[0]), &memstats.other_sys)
}
h_allspans = new
h.allspans = (**mspan)(sp.array)
}
h_allspans = append(h_allspans, s)
h.nspan = uint32(len(h_allspans))
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.