Add extents information to mallocstats output

- Show number/bytes of extents of each size that are dirty, muzzy, retained.

include/jemalloc/internal/arena_externs.h

@@ -25,7 +25,8 @@ void arena_basic_stats_merge(tsdn_t *tsdn, arena_t *arena,
 void arena_stats_merge(tsdn_t *tsdn, arena_t *arena, unsigned *nthreads,
     const char **dss, ssize_t *dirty_decay_ms, ssize_t *muzzy_decay_ms,
     size_t *nactive, size_t *ndirty, size_t *nmuzzy, arena_stats_t *astats,
-    bin_stats_t *bstats, arena_stats_large_t *lstats);
+    bin_stats_t *bstats, arena_stats_large_t *lstats,
+    arena_stats_extents_t *estats);
 void arena_extents_dirty_dalloc(tsdn_t *tsdn, arena_t *arena,
     extent_hooks_t **r_extent_hooks, extent_t *extent);
 #ifdef JEMALLOC_JET

include/jemalloc/internal/arena_stats.h

@@ -50,6 +50,22 @@ struct arena_stats_decay_s {
 	arena_stats_u64_t	purged;
 };
 
+typedef struct arena_stats_extents_s arena_stats_extents_t;
+struct arena_stats_extents_s {
+	/*
+	 * Stats for a given index in the range [0, SC_NPSIZES] in an extents_t.
+	 * We track both bytes and # of extents: two extents in the same bucket
+	 * may have different sizes if adjacent size classes differ by more than
+	 * a page, so bytes cannot always be derived from # of extents.
+	 */
+	atomic_zu_t ndirty;
+	atomic_zu_t dirty_bytes;
+	atomic_zu_t nmuzzy;
+	atomic_zu_t muzzy_bytes;
+	atomic_zu_t nretained;
+	atomic_zu_t retained_bytes;
+};
+
 /*
  * Arena stats.  Note that fields marked "derived" are not directly maintained
  * within the arena code; rather their values are derived during stats merge

include/jemalloc/internal/ctl.h

@@ -42,6 +42,7 @@ typedef struct ctl_arena_stats_s {
 
 	bin_stats_t bstats[SC_NBINS];
 	arena_stats_large_t lstats[SC_NSIZES - SC_NBINS];
+	arena_stats_extents_t estats[SC_NPSIZES];
 } ctl_arena_stats_t;
 
 typedef struct ctl_stats_s {

include/jemalloc/internal/extent_externs.h

@@ -31,6 +31,10 @@ bool extents_init(tsdn_t *tsdn, extents_t *extents, extent_state_t state,
     bool delay_coalesce);
 extent_state_t extents_state_get(const extents_t *extents);
 size_t extents_npages_get(extents_t *extents);
+/* Get the number of extents in the given page size index. */
+size_t extents_nextents_get(extents_t *extents, pszind_t ind);
+/* Get the sum total bytes of the extents in the given page size index. */
+size_t extents_nbytes_get(extents_t *extents, pszind_t ind);
 extent_t *extents_alloc(tsdn_t *tsdn, arena_t *arena,
     extent_hooks_t **r_extent_hooks, extents_t *extents, void *new_addr,
     size_t size, size_t pad, size_t alignment, bool slab, szind_t szind,

include/jemalloc/internal/extent_structs.h

@@ -184,6 +184,8 @@ struct extents_s {
 	 * Synchronization: mtx.
 	 */
 	extent_heap_t		heaps[SC_NPSIZES + 1];
+	atomic_zu_t		nextents[SC_NPSIZES + 1];
+	atomic_zu_t		nbytes[SC_NPSIZES + 1];
 
 	/*
 	 * Bitmap for which set bits correspond to non-empty heaps.

include/jemalloc/internal/stats.h

@@ -10,7 +10,8 @@
     OPTION('a',		unmerged,	config_stats,	false)		\
     OPTION('b',		bins,		true,		false)		\
     OPTION('l',		large,		true,		false)		\
-    OPTION('x',		mutex,		true,		false)
+    OPTION('x',		mutex,		true,		false)		\
+    OPTION('e',		extents,	true,		false)
 
 enum {
 #define OPTION(o, v, d, s) stats_print_option_num_##v,