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| author | Michael Anthony Knyszek <mknyszek@google.com> | 2019-09-18 15:03:50 +0000 |
|---|---|---|
| committer | Michael Knyszek <mknyszek@google.com> | 2019-11-08 16:21:04 +0000 |
| commit | ae4534e6598fe905d3ebefae44afef07e853b1d0 (patch) | |
| tree | 3052e5f9bb07210295a69ea8eebfe6be4cb141b8 /src/runtime/mstats.go | |
| parent | 814c5058bbbd70e706b0305d823e83aa0112d5a4 (diff) | |
| download | go-ae4534e6598fe905d3ebefae44afef07e853b1d0.tar.xz | |
runtime: ensure heap memstats are updated atomically
For the most part, heap memstats are already updated atomically when
passed down to OS-level memory functions (e.g. sysMap). Elsewhere,
however, they're updated with the heap lock.
In order to facilitate holding the heap lock for less time during
allocation paths, this change more consistently makes the update of
these statistics atomic by calling mSysStat{Inc,Dec} appropriately
instead of simply adding or subtracting. It also ensures these values
are loaded atomically.
Furthermore, an undocumented but safe update condition for these
memstats is during STW, at which point using atomics is unnecessary.
This change also documents this condition in mstats.go.
Updates #35112.
Change-Id: I87d0b6c27b98c88099acd2563ea23f8da1239b66
Reviewed-on: https://go-review.googlesource.com/c/go/+/196638
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Diffstat (limited to 'src/runtime/mstats.go')
| -rw-r--r-- | src/runtime/mstats.go | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/src/runtime/mstats.go b/src/runtime/mstats.go index a6866e3a15..f40bccad17 100644 --- a/src/runtime/mstats.go +++ b/src/runtime/mstats.go @@ -31,7 +31,7 @@ type mstats struct { nfree uint64 // number of frees // Statistics about malloc heap. - // Protected by mheap.lock + // Updated atomically, or with the world stopped. // // Like MemStats, heap_sys and heap_inuse do not count memory // in manually-managed spans. @@ -47,15 +47,15 @@ type mstats struct { // Statistics about allocation of low-level fixed-size structures. // Protected by FixAlloc locks. - stacks_inuse uint64 // bytes in manually-managed stack spans + stacks_inuse uint64 // bytes in manually-managed stack spans; updated atomically or during STW stacks_sys uint64 // only counts newosproc0 stack in mstats; differs from MemStats.StackSys mspan_inuse uint64 // mspan structures mspan_sys uint64 mcache_inuse uint64 // mcache structures mcache_sys uint64 buckhash_sys uint64 // profiling bucket hash table - gc_sys uint64 - other_sys uint64 + gc_sys uint64 // updated atomically or during STW + other_sys uint64 // updated atomically or during STW // Statistics about garbage collector. // Protected by mheap or stopping the world during GC. |