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author | Michael Anthony Knyszek <mknyszek@google.com> | 2020-08-03 20:35:40 +0000 |
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committer | Michael Knyszek <mknyszek@google.com> | 2020-10-26 18:28:20 +0000 |
commit | f77a9025f1e4bf4bb3e2b582d13cce5f19c1ca51 (patch) | |
tree | 0d32f60f00704a0ce70dab1e1d6bebf2902bbd63 /src/runtime/mstats.go | |
parent | fe7ff71185cf30f9bdee3e8d8897e8b6069ad02e (diff) | |
download | go-f77a9025f1e4bf4bb3e2b582d13cce5f19c1ca51.tar.gz go-f77a9025f1e4bf4bb3e2b582d13cce5f19c1ca51.zip |
runtime: replace some memstats with consistent stats
This change replaces stacks_inuse, gcWorkBufInUse and
gcProgPtrScalarBitsInUse with their corresponding consistent stats. It
also adds checks to make sure the rest of the sharded stats line up with
existing stats in updatememstats.
Change-Id: I17d0bd181aedb5c55e09c8dff18cef5b2a3a14e3
Reviewed-on: https://go-review.googlesource.com/c/go/+/247038
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Diffstat (limited to 'src/runtime/mstats.go')
-rw-r--r-- | src/runtime/mstats.go | 73 |
1 files changed, 60 insertions, 13 deletions
diff --git a/src/runtime/mstats.go b/src/runtime/mstats.go index 76546c0f0c..4363eff1e0 100644 --- a/src/runtime/mstats.go +++ b/src/runtime/mstats.go @@ -40,19 +40,25 @@ type mstats struct { // computed on the fly by updatememstats. heap_objects uint64 // total number of allocated objects + // Statistics about stacks. + stacks_inuse uint64 // bytes in manually-managed stack spans; computed by updatememstats + stacks_sys sysMemStat // only counts newosproc0 stack in mstats; differs from MemStats.StackSys + // Statistics about allocation of low-level fixed-size structures. // Protected by FixAlloc locks. - stacks_inuse uint64 // bytes in manually-managed stack spans; updated atomically or during STW - stacks_sys sysMemStat // only counts newosproc0 stack in mstats; differs from MemStats.StackSys - mspan_inuse uint64 // mspan structures - mspan_sys sysMemStat - mcache_inuse uint64 // mcache structures - mcache_sys sysMemStat - buckhash_sys sysMemStat // profiling bucket hash table - gcWorkBufInUse uint64 // updated atomically or during STW - gcProgPtrScalarBitsInUse uint64 // updated atomically or during STW + mspan_inuse uint64 // mspan structures + mspan_sys sysMemStat + mcache_inuse uint64 // mcache structures + mcache_sys sysMemStat + buckhash_sys sysMemStat // profiling bucket hash table + + // Statistics about GC overhead. + gcWorkBufInUse uint64 // computed by updatememstats + gcProgPtrScalarBitsInUse uint64 // computed by updatememstats gcMiscSys sysMemStat // updated atomically or during STW - other_sys sysMemStat // updated atomically or during STW + + // Miscellaneous statistics. + other_sys sysMemStat // updated atomically or during STW // Statistics about the garbage collector. @@ -577,6 +583,10 @@ func readGCStats_m(pauses *[]uint64) { *pauses = p[:n+n+3] } +// Updates the memstats structure. +// +// The world must be stopped. +// //go:nowritebarrier func updatememstats() { // Flush mcaches to mcentral before doing anything else. @@ -591,9 +601,6 @@ func updatememstats() { memstats.mcache_sys.load() + memstats.buckhash_sys.load() + memstats.gcMiscSys.load() + memstats.other_sys.load() - // We also count stacks_inuse, gcWorkBufInUse, and gcProgPtrScalarBitsInUse as sys memory. - memstats.sys += memstats.stacks_inuse + memstats.gcWorkBufInUse + memstats.gcProgPtrScalarBitsInUse - // Calculate memory allocator stats. // During program execution we only count number of frees and amount of freed memory. // Current number of alive objects in the heap and amount of alive heap memory @@ -641,6 +648,9 @@ func updatememstats() { smallFree += uint64(c.smallFreeCount[i]) * uint64(class_to_size[i]) } } + // Collect consistent stats, which are the source-of-truth in the some cases. + var consStats heapStatsDelta + memstats.heapStats.unsafeRead(&consStats) totalFree += smallFree @@ -651,6 +661,43 @@ func updatememstats() { memstats.total_alloc = totalAlloc memstats.alloc = totalAlloc - totalFree memstats.heap_objects = memstats.nmalloc - memstats.nfree + + memstats.stacks_inuse = uint64(consStats.inStacks) + memstats.gcWorkBufInUse = uint64(consStats.inWorkBufs) + memstats.gcProgPtrScalarBitsInUse = uint64(consStats.inPtrScalarBits) + + // We also count stacks_inuse, gcWorkBufInUse, and gcProgPtrScalarBitsInUse as sys memory. + memstats.sys += memstats.stacks_inuse + memstats.gcWorkBufInUse + memstats.gcProgPtrScalarBitsInUse + + // The world is stopped, so the consistent stats (after aggregation) + // should be identical to some combination of memstats. In particular: + // + // * heap_inuse == inHeap + // * heap_released == released + // * heap_sys - heap_released == committed - inStacks - inWorkBufs - inPtrScalarBits + // + // Check if that's actually true. + // + // TODO(mknyszek): Maybe don't throw here. It would be bad if a + // bug in otherwise benign accounting caused the whole application + // to crash. + if memstats.heap_inuse != uint64(consStats.inHeap) { + print("runtime: heap_inuse=", memstats.heap_inuse, "\n") + print("runtime: consistent value=", consStats.inHeap, "\n") + throw("heap_inuse and consistent stats are not equal") + } + if memstats.heap_released != uint64(consStats.released) { + print("runtime: heap_released=", memstats.heap_released, "\n") + print("runtime: consistent value=", consStats.released, "\n") + throw("heap_released and consistent stats are not equal") + } + globalRetained := memstats.heap_sys.load() - memstats.heap_released + consRetained := uint64(consStats.committed - consStats.inStacks - consStats.inWorkBufs - consStats.inPtrScalarBits) + if globalRetained != consRetained { + print("runtime: global value=", globalRetained, "\n") + print("runtime: consistent value=", consRetained, "\n") + throw("measures of the retained heap are not equal") + } } // flushmcache flushes the mcache of allp[i]. |