runtime: add per-M caches for MemStats

Avoid touching centralized state during
memory manager operations.

R=mirtchovski
CC=golang-dev, rsc
https://golang.org/cl/4766042

diff --git a/src/pkg/runtime/malloc.h b/src/pkg/runtime/malloc.h
index 2865317ef65cfd9d0c3018a26311cc62cee28630..5bc80f4df954b6c56271e76f8829ab0c28cd57da 100644 (file)
--- a/src/pkg/runtime/malloc.h
+++ b/src/pkg/runtime/malloc.h
@@ -268,7 +268,7 @@ struct MCache
        uint64 size;
        int64 local_cachealloc; // bytes allocated (or freed) from cache since last lock of heap
        int64 local_objects;    // objects allocated (or freed) from cache since last lock of heap
-       int64 local_alloc;      // bytes allocated and still in use since last lock of heap
+       int64 local_alloc;      // bytes allocated (or freed) since last lock of heap
        int64 local_total_alloc;        // bytes allocated (even if freed) since last lock of heap
        int64 local_nmalloc;    // number of mallocs since last lock of heap
        int64 local_nfree;      // number of frees since last lock of heap