HPA: Add an nevictions counter.

I.e. the number of times we've purged a hugepage-sized region.

include/jemalloc/internal/hpa.h

@@ -6,10 +6,12 @@
 #include "jemalloc/internal/pai.h"
 #include "jemalloc/internal/psset.h"
 
-/* Used only by CTL; not actually stored here (i.e., all derived). */
+/* Completely derived; only used by CTL. */
 typedef struct hpa_shard_stats_s hpa_shard_stats_t;
 struct hpa_shard_stats_s {
 	psset_stats_t psset_stats;
+	/* The stat version of the nevictions counter. */
+	uint64_t nevictions;
 };
 
 typedef struct hpa_shard_s hpa_shard_t;
@@ -69,6 +71,14 @@ struct hpa_shard_s {
 	/* The arena ind we're associated with. */
 	unsigned ind;
 	emap_t *emap;
+
+	/*
+	 * The number of times we've purged a hugepage.  Each eviction purges a
+	 * single hugepage.
+	 *
+	 * Guarded by the grow mutex.
+	 */
+	uint64_t nevictions;
 };
 
 /*

src/ctl.c

@@ -220,6 +220,7 @@ CTL_PROTO(stats_arenas_i_extents_j_dirty_bytes)
 CTL_PROTO(stats_arenas_i_extents_j_muzzy_bytes)
 CTL_PROTO(stats_arenas_i_extents_j_retained_bytes)
 INDEX_PROTO(stats_arenas_i_extents_j)
+CTL_PROTO(stats_arenas_i_hpa_shard_nevictions)
 CTL_PROTO(stats_arenas_i_hpa_shard_full_slabs_npageslabs_huge)
 CTL_PROTO(stats_arenas_i_hpa_shard_full_slabs_nactive_huge)
 CTL_PROTO(stats_arenas_i_hpa_shard_full_slabs_ninactive_huge)
@@ -655,7 +656,8 @@ static const ctl_named_node_t stats_arenas_i_hpa_shard_node[] = {
 	{NAME("full_slabs"),	CHILD(named,
 	    stats_arenas_i_hpa_shard_full_slabs)},
 	{NAME("nonfull_slabs"),	CHILD(indexed,
-	    stats_arenas_i_hpa_shard_nonfull_slabs)}
+	    stats_arenas_i_hpa_shard_nonfull_slabs)},
+	{NAME("nevictions"),	CTL(stats_arenas_i_hpa_shard_nevictions)}
 };
 
 static const ctl_named_node_t stats_arenas_i_node[] = {
@@ -3372,6 +3374,9 @@ stats_arenas_i_extents_j_index(tsdn_t *tsdn, const size_t *mib,
 	return super_stats_arenas_i_extents_j_node;
 }
 
+CTL_RO_CGEN(config_stats, stats_arenas_i_hpa_shard_nevictions,
+    arenas_i(mib[2])->astats->hpastats.nevictions, uint64_t);
+
 /* Full, huge */
 CTL_RO_CGEN(config_stats, stats_arenas_i_hpa_shard_full_slabs_npageslabs_huge,
     arenas_i(mib[2])->astats->hpastats.psset_stats.full_slabs.npageslabs_huge,

src/hpa.c

@@ -74,6 +74,7 @@ hpa_shard_init(hpa_shard_t *shard, emap_t *emap, base_t *base,
 	shard->eden_len = 0;
 	shard->ind = ind;
 	shard->emap = emap;
+	shard->nevictions = 0;
 
 	/*
 	 * Fill these in last, so that if an hpa_shard gets used despite
@@ -97,14 +98,18 @@ hpa_shard_init(hpa_shard_t *shard, emap_t *emap, base_t *base,
 void
 hpa_shard_stats_accum(hpa_shard_stats_t *dst, hpa_shard_stats_t *src) {
 	psset_stats_accum(&dst->psset_stats, &src->psset_stats);
+	dst->nevictions += src->nevictions;
 }
 
 void
 hpa_shard_stats_merge(tsdn_t *tsdn, hpa_shard_t *shard,
     hpa_shard_stats_t *dst) {
+	malloc_mutex_lock(tsdn, &shard->grow_mtx);
 	malloc_mutex_lock(tsdn, &shard->mtx);
 	psset_stats_accum(&dst->psset_stats, &shard->psset.stats);
+	dst->nevictions += shard->nevictions;
 	malloc_mutex_unlock(tsdn, &shard->mtx);
+	malloc_mutex_unlock(tsdn, &shard->grow_mtx);
 }
 
 static hpdata_t *
@@ -238,6 +243,7 @@ hpa_handle_ps_eviction(tsdn_t *tsdn, hpa_shard_t *shard, hpdata_t *ps) {
 	hpa_dehugify(ps);
 
 	malloc_mutex_lock(tsdn, &shard->grow_mtx);
+	shard->nevictions++;
 	hpdata_list_prepend(&shard->unused_slabs, ps);
 	malloc_mutex_unlock(tsdn, &shard->grow_mtx);
 }
@@ -353,6 +359,7 @@ hpa_alloc_psset(tsdn_t *tsdn, hpa_shard_t *shard, size_t size) {
 	malloc_mutex_lock(tsdn, &shard->mtx);
 	edata = edata_cache_small_get(tsdn, &shard->ecs);
 	if (edata == NULL) {
+		shard->nevictions++;
 		malloc_mutex_unlock(tsdn, &shard->mtx);
 		malloc_mutex_unlock(tsdn, &shard->grow_mtx);
 		hpa_handle_ps_eviction(tsdn, shard, ps);
@@ -371,11 +378,8 @@ hpa_alloc_psset(tsdn_t *tsdn, hpa_shard_t *shard, size_t size) {
 		hpdata_unreserve(ps, edata_addr_get(edata),
 		    edata_size_get(edata));
 		edata_cache_small_put(tsdn, &shard->ecs, edata);
-		/*
+
-		 * Technically the same as fallthrough at the time of this
+		shard->nevictions++;
-		 * writing, but consistent with the error handling in the rest
-		 * of the function.
-		 */
 		malloc_mutex_unlock(tsdn, &shard->mtx);
 		malloc_mutex_unlock(tsdn, &shard->grow_mtx);
 		hpa_handle_ps_eviction(tsdn, shard, ps);

src/stats.c

@@ -661,12 +661,14 @@ stats_arena_extents_print(emitter_t *emitter, unsigned i) {
 }
 
 static void
-stats_arena_hpa_shard_print(emitter_t *emitter, unsigned i) {
+stats_arena_hpa_shard_print(emitter_t *emitter, unsigned i, uint64_t uptime) {
 	emitter_row_t header_row;
 	emitter_row_init(&header_row);
 	emitter_row_t row;
 	emitter_row_init(&row);
 
+	uint64_t nevictions;
+
 	size_t npageslabs_huge;
 	size_t nactive_huge;
 	size_t ninactive_huge;
@@ -675,6 +677,9 @@ stats_arena_hpa_shard_print(emitter_t *emitter, unsigned i) {
 	size_t nactive_nonhuge;
 	size_t ninactive_nonhuge;
 
+	CTL_M2_GET("stats.arenas.0.hpa_shard.nevictions",
+	    i, &nevictions, uint64_t);
+
 	CTL_M2_GET("stats.arenas.0.hpa_shard.full_slabs.npageslabs_huge",
 	    i, &npageslabs_huge, size_t);
 	CTL_M2_GET("stats.arenas.0.hpa_shard.full_slabs.nactive_huge",
@@ -696,13 +701,18 @@ stats_arena_hpa_shard_print(emitter_t *emitter, unsigned i) {
 
 	emitter_table_printf(emitter,
 	    "HPA shard stats:\n"
+	    "  Evictions: %" FMTu64 " (%" FMTu64 " / sec)\n"
 	    "  In full slabs:\n"
 	    "      npageslabs: %zu huge, %zu nonhuge\n"
 	    "      nactive: %zu huge, %zu nonhuge \n"
 	    "      ninactive: %zu huge, %zu nonhuge \n",
-	    npageslabs_huge, npageslabs_nonhuge, nactive_huge, nactive_nonhuge,
+	    nevictions, rate_per_second(nevictions, uptime),
+	    npageslabs_huge, npageslabs_nonhuge,
+	    nactive_huge, nactive_nonhuge,
 	    ninactive_huge, ninactive_nonhuge);
 	emitter_json_object_kv_begin(emitter, "hpa_shard");
+	emitter_json_kv(emitter, "nevictions", emitter_type_uint64,
+	    &nevictions);
 	emitter_json_object_kv_begin(emitter, "full_slabs");
 	emitter_json_kv(emitter, "npageslabs_huge", emitter_type_size,
 	    &npageslabs_huge);
@@ -1137,7 +1147,7 @@ stats_arena_print(emitter_t *emitter, unsigned i, bool bins, bool large,
 		stats_arena_extents_print(emitter, i);
 	}
 	if (hpa) {
-		stats_arena_hpa_shard_print(emitter, i);
+		stats_arena_hpa_shard_print(emitter, i, uptime);
 	}
 }