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runtime: make the span allocation purpose more explicit

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This change modifies mheap's span allocation API to have each caller
declare a purpose, defined as a new enum called spanAllocType.

The purpose behind this change is two-fold:
1. Tight control over who gets to allocate heap memory is, generally
   speaking, a good thing. Every codepath that allocates heap memory
   places additional implicit restrictions on the allocator. A notable
   example of a restriction is work bufs coming from heap memory: write
   barriers are not allowed in allocation paths because then we could
   have a situation where the allocator calls into the allocator.
2. Memory statistic updating is explicit. Instead of passing an opaque
   pointer for statistic updating, which places restrictions on how that
   statistic may be updated, we use the spanAllocType to determine which
   statistic to update and how.

We also take this opportunity to group all the statistic updating code
together, which should make the accounting code a little easier to
follow.

Change-Id: Ic0b0898959ba2a776f67122f0e36c9d7d60e3085
Reviewed-on: https://go-review.googlesource.com/c/go/+/246970
Trust: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
This commit is contained in:
Michael Anthony Knyszek 2020-07-29 19:00:37 +00:00 • committed by Michael Knyszek
parent c863849800
commit dc02578ac8
4 changed files with 68 additions and 30 deletions
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12
src/runtime/stack.go
View file

@ -187,7 +187,7 @@ func stackpoolalloc(order uint8) gclinkptr {
lockWithRankMayAcquire(&mheap_.lock, lockRankMheap)
if s == nil {
// no free stacks. Allocate another span worth.
s = mheap_.allocManual(_StackCacheSize>>_PageShift, &memstats.stacks_inuse)
s = mheap_.allocManual(_StackCacheSize>>_PageShift, spanAllocStack)
if s == nil {
throw("out of memory")
}
@ -251,7 +251,7 @@ func stackpoolfree(x gclinkptr, order uint8) {
stackpool[order].item.span.remove(s)
s.manualFreeList = 0
osStackFree(s)
mheap_.freeManual(s, &memstats.stacks_inuse)
mheap_.freeManual(s, spanAllocStack)
}
}
@ -396,7 +396,7 @@ func stackalloc(n uint32) stack {
if s == nil {
// Allocate a new stack from the heap.
s = mheap_.allocManual(npage, &memstats.stacks_inuse)
s = mheap_.allocManual(npage, spanAllocStack)
if s == nil {
throw("out of memory")
}
@ -480,7 +480,7 @@ func stackfree(stk stack) {
// Free the stack immediately if we're
// sweeping.
osStackFree(s)
mheap_.freeManual(s, &memstats.stacks_inuse)
mheap_.freeManual(s, spanAllocStack)
} else {
// If the GC is running, we can't return a
// stack span to the heap because it could be
@ -1193,7 +1193,7 @@ func freeStackSpans() {
list.remove(s)
s.manualFreeList = 0
osStackFree(s)
mheap_.freeManual(s, &memstats.stacks_inuse)
mheap_.freeManual(s, spanAllocStack)
}
s = next
}
@ -1207,7 +1207,7 @@ func freeStackSpans() {
next := s.next
stackLarge.free[i].remove(s)
osStackFree(s)
mheap_.freeManual(s, &memstats.stacks_inuse)
mheap_.freeManual(s, spanAllocStack)
s = next
}
}