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Diffstat (limited to 'src/runtime/mstats.go')
| -rw-r--r-- | src/runtime/mstats.go | 340 |
1 files changed, 340 insertions, 0 deletions
diff --git a/src/runtime/mstats.go b/src/runtime/mstats.go new file mode 100644 index 0000000000..19b6833a32 --- /dev/null +++ b/src/runtime/mstats.go @@ -0,0 +1,340 @@ +// 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. + +// Memory statistics + +package runtime + +import "unsafe" + +// Statistics. +// Shared with Go: if you edit this structure, also edit type MemStats in mem.go. +type mstats struct { + // General statistics. + alloc uint64 // bytes allocated and still in use + total_alloc uint64 // bytes allocated (even if freed) + sys uint64 // bytes obtained from system (should be sum of xxx_sys below, no locking, approximate) + nlookup uint64 // number of pointer lookups + nmalloc uint64 // number of mallocs + nfree uint64 // number of frees + + // Statistics about malloc heap. + // protected by mheap.lock + heap_alloc uint64 // bytes allocated and still in use + heap_sys uint64 // bytes obtained from system + heap_idle uint64 // bytes in idle spans + heap_inuse uint64 // bytes in non-idle spans + heap_released uint64 // bytes released to the os + heap_objects uint64 // total number of allocated objects + + // Statistics about allocation of low-level fixed-size structures. + // Protected by FixAlloc locks. + stacks_inuse uint64 // this number is included in heap_inuse above + stacks_sys uint64 // always 0 in mstats + 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 + + // Statistics about garbage collector. + // Protected by mheap or stopping the world during GC. + next_gc uint64 // next gc (in heap_alloc time) + last_gc uint64 // last gc (in absolute time) + pause_total_ns uint64 + pause_ns [256]uint64 // circular buffer of recent gc pause lengths + pause_end [256]uint64 // circular buffer of recent gc end times (nanoseconds since 1970) + numgc uint32 + enablegc bool + debuggc bool + + // Statistics about allocation size classes. + + by_size [_NumSizeClasses]struct { + size uint32 + nmalloc uint64 + nfree uint64 + } + + tinyallocs uint64 // number of tiny allocations that didn't cause actual allocation; not exported to go directly +} + +var memstats mstats + +// Note: the MemStats struct should be kept in sync with +// struct MStats in malloc.h + +// A MemStats records statistics about the memory allocator. +type MemStats struct { + // General statistics. + Alloc uint64 // bytes allocated and still in use + TotalAlloc uint64 // bytes allocated (even if freed) + Sys uint64 // bytes obtained from system (sum of XxxSys below) + Lookups uint64 // number of pointer lookups + Mallocs uint64 // number of mallocs + Frees uint64 // number of frees + + // Main allocation heap statistics. + HeapAlloc uint64 // bytes allocated and still in use + HeapSys uint64 // bytes obtained from system + HeapIdle uint64 // bytes in idle spans + HeapInuse uint64 // bytes in non-idle span + HeapReleased uint64 // bytes released to the OS + HeapObjects uint64 // total number of allocated objects + + // Low-level fixed-size structure allocator statistics. + // Inuse is bytes used now. + // Sys is bytes obtained from system. + StackInuse uint64 // bytes used by stack allocator + StackSys uint64 + MSpanInuse uint64 // mspan structures + MSpanSys uint64 + MCacheInuse uint64 // mcache structures + MCacheSys uint64 + BuckHashSys uint64 // profiling bucket hash table + GCSys uint64 // GC metadata + OtherSys uint64 // other system allocations + + // Garbage collector statistics. + NextGC uint64 // next collection will happen when HeapAlloc ≥ this amount + LastGC uint64 // end time of last collection (nanoseconds since 1970) + PauseTotalNs uint64 + PauseNs [256]uint64 // circular buffer of recent GC pause durations, most recent at [(NumGC+255)%256] + PauseEnd [256]uint64 // circular buffer of recent GC pause end times + NumGC uint32 + EnableGC bool + DebugGC bool + + // Per-size allocation statistics. + // 61 is NumSizeClasses in the C code. + BySize [61]struct { + Size uint32 + Mallocs uint64 + Frees uint64 + } +} + +// Size of the trailing by_size array differs between Go and C, +// and all data after by_size is local to runtime, not exported. +// NumSizeClasses was changed, but we can not change Go struct because of backward compatibility. +// sizeof_C_MStats is what C thinks about size of Go struct. +var sizeof_C_MStats = unsafe.Offsetof(memstats.by_size) + 61*unsafe.Sizeof(memstats.by_size[0]) + +func init() { + var memStats MemStats + if sizeof_C_MStats != unsafe.Sizeof(memStats) { + println(sizeof_C_MStats, unsafe.Sizeof(memStats)) + throw("MStats vs MemStatsType size mismatch") + } +} + +// ReadMemStats populates m with memory allocator statistics. +func ReadMemStats(m *MemStats) { + // Have to acquire worldsema to stop the world, + // because stoptheworld can only be used by + // one goroutine at a time, and there might be + // a pending garbage collection already calling it. + semacquire(&worldsema, false) + gp := getg() + gp.m.preemptoff = "read mem stats" + systemstack(stoptheworld) + + systemstack(func() { + readmemstats_m(m) + }) + + gp.m.preemptoff = "" + gp.m.locks++ + semrelease(&worldsema) + systemstack(starttheworld) + gp.m.locks-- +} + +func readmemstats_m(stats *MemStats) { + updatememstats(nil) + + // Size of the trailing by_size array differs between Go and C, + // NumSizeClasses was changed, but we can not change Go struct because of backward compatibility. + memmove(unsafe.Pointer(stats), unsafe.Pointer(&memstats), sizeof_C_MStats) + + // Stack numbers are part of the heap numbers, separate those out for user consumption + stats.StackSys = stats.StackInuse + stats.HeapInuse -= stats.StackInuse + stats.HeapSys -= stats.StackInuse +} + +//go:linkname readGCStats runtime/debug.readGCStats +func readGCStats(pauses *[]uint64) { + systemstack(func() { + readGCStats_m(pauses) + }) +} + +func readGCStats_m(pauses *[]uint64) { + p := *pauses + // Calling code in runtime/debug should make the slice large enough. + if cap(p) < len(memstats.pause_ns)+3 { + throw("short slice passed to readGCStats") + } + + // Pass back: pauses, pause ends, last gc (absolute time), number of gc, total pause ns. + lock(&mheap_.lock) + + n := memstats.numgc + if n > uint32(len(memstats.pause_ns)) { + n = uint32(len(memstats.pause_ns)) + } + + // The pause buffer is circular. The most recent pause is at + // pause_ns[(numgc-1)%len(pause_ns)], and then backward + // from there to go back farther in time. We deliver the times + // most recent first (in p[0]). + p = p[:cap(p)] + for i := uint32(0); i < n; i++ { + j := (memstats.numgc - 1 - i) % uint32(len(memstats.pause_ns)) + p[i] = memstats.pause_ns[j] + p[n+i] = memstats.pause_end[j] + } + + p[n+n] = memstats.last_gc + p[n+n+1] = uint64(memstats.numgc) + p[n+n+2] = memstats.pause_total_ns + unlock(&mheap_.lock) + *pauses = p[:n+n+3] +} + +//go:nowritebarrier +func updatememstats(stats *gcstats) { + if stats != nil { + *stats = gcstats{} + } + for mp := allm; mp != nil; mp = mp.alllink { + if stats != nil { + src := (*[unsafe.Sizeof(gcstats{}) / 8]uint64)(unsafe.Pointer(&mp.gcstats)) + dst := (*[unsafe.Sizeof(gcstats{}) / 8]uint64)(unsafe.Pointer(stats)) + for i, v := range src { + dst[i] += v + } + mp.gcstats = gcstats{} + } + } + + memstats.mcache_inuse = uint64(mheap_.cachealloc.inuse) + memstats.mspan_inuse = uint64(mheap_.spanalloc.inuse) + memstats.sys = memstats.heap_sys + memstats.stacks_sys + memstats.mspan_sys + + memstats.mcache_sys + memstats.buckhash_sys + memstats.gc_sys + memstats.other_sys + + // Calculate memory allocator stats. + // During program execution we only count number of frees and amount of freed memory. + // Current number of alive object in the heap and amount of alive heap memory + // are calculated by scanning all spans. + // Total number of mallocs is calculated as number of frees plus number of alive objects. + // Similarly, total amount of allocated memory is calculated as amount of freed memory + // plus amount of alive heap memory. + memstats.alloc = 0 + memstats.total_alloc = 0 + memstats.nmalloc = 0 + memstats.nfree = 0 + for i := 0; i < len(memstats.by_size); i++ { + memstats.by_size[i].nmalloc = 0 + memstats.by_size[i].nfree = 0 + } + + // Flush MCache's to MCentral. + systemstack(flushallmcaches) + + // Aggregate local stats. + cachestats() + + // Scan all spans and count number of alive objects. + lock(&mheap_.lock) + for i := uint32(0); i < mheap_.nspan; i++ { + s := h_allspans[i] + if s.state != mSpanInUse { + continue + } + if s.sizeclass == 0 { + memstats.nmalloc++ + memstats.alloc += uint64(s.elemsize) + } else { + memstats.nmalloc += uint64(s.ref) + memstats.by_size[s.sizeclass].nmalloc += uint64(s.ref) + memstats.alloc += uint64(s.ref) * uint64(s.elemsize) + } + } + unlock(&mheap_.lock) + + // Aggregate by size class. + smallfree := uint64(0) + memstats.nfree = mheap_.nlargefree + for i := 0; i < len(memstats.by_size); i++ { + memstats.nfree += mheap_.nsmallfree[i] + memstats.by_size[i].nfree = mheap_.nsmallfree[i] + memstats.by_size[i].nmalloc += mheap_.nsmallfree[i] + smallfree += uint64(mheap_.nsmallfree[i]) * uint64(class_to_size[i]) + } + memstats.nfree += memstats.tinyallocs + memstats.nmalloc += memstats.nfree + + // Calculate derived stats. + memstats.total_alloc = uint64(memstats.alloc) + uint64(mheap_.largefree) + smallfree + memstats.heap_alloc = memstats.alloc + memstats.heap_objects = memstats.nmalloc - memstats.nfree +} + +//go:nowritebarrier +func cachestats() { + for i := 0; ; i++ { + p := allp[i] + if p == nil { + break + } + c := p.mcache + if c == nil { + continue + } + purgecachedstats(c) + } +} + +//go:nowritebarrier +func flushallmcaches() { + for i := 0; ; i++ { + p := allp[i] + if p == nil { + break + } + c := p.mcache + if c == nil { + continue + } + mCache_ReleaseAll(c) + stackcache_clear(c) + } +} + +//go:nosplit +func purgecachedstats(c *mcache) { + // Protected by either heap or GC lock. + h := &mheap_ + memstats.heap_alloc += uint64(c.local_cachealloc) + c.local_cachealloc = 0 + if trace.enabled { + traceHeapAlloc() + } + memstats.tinyallocs += uint64(c.local_tinyallocs) + c.local_tinyallocs = 0 + memstats.nlookup += uint64(c.local_nlookup) + c.local_nlookup = 0 + h.largefree += uint64(c.local_largefree) + c.local_largefree = 0 + h.nlargefree += uint64(c.local_nlargefree) + c.local_nlargefree = 0 + for i := 0; i < len(c.local_nsmallfree); i++ { + h.nsmallfree[i] += uint64(c.local_nsmallfree[i]) + c.local_nsmallfree[i] = 0 + } +} |