Move empty slab tracking to the psset.

We're moving towards a world in which purging decisions are less rigidly
enforced at a single-hugepage level.  In that world, it makes sense to keep
around some hpdatas which are not completely purged, in which case we'll need to
track them.

include/jemalloc/internal/hpa.h

@@ -8,14 +8,6 @@
 
 typedef struct hpa_shard_nonderived_stats_s hpa_shard_nonderived_stats_t;
 struct hpa_shard_nonderived_stats_s {
-	/*
-	 * The number of times we've fully purged a hugepage and evicted it from
-	 * the psset.
-	 *
-	 * Guarded by grow_mtx.
-	 */
-	uint64_t nevictions;
-
 	/*
 	 * The number of times we've purged within a hugepage.
 	 *
@@ -80,15 +72,6 @@ struct hpa_shard_s {
 	 */
 	size_t alloc_max;
 
-	/*
-	 * Slabs currently purged away.  They are hugepage-sized and
-	 * hugepage-aligned, but have had pages_nohuge and pages_purge_forced
-	 * called on them.
-	 *
-	 * Guarded by grow_mtx.
-	 */
-	hpdata_list_t unused_slabs;
-
 	/*
 	 * How many grow operations have occurred.
 	 *

include/jemalloc/internal/hpdata.h

@@ -52,14 +52,17 @@ struct hpdata_s {
 	 */
 	bool h_updating;
 
+	/* Whether or not the hpdata is in a psset. */
+	bool h_in_psset;
+
 	union {
-		/* When nonempty, used by the psset bins. */
+		/* When nonempty (and also nonfull), used by the psset bins. */
 		phn(hpdata_t) ph_link;
 		/*
 		 * When empty (or not corresponding to any hugepage), list
 		 * linkage.
 		 */
-		ql_elm(hpdata_t) ql_link;
+		ql_elm(hpdata_t) ql_link_empty;
 	};
 
 	/* The length of the largest contiguous sequence of inactive pages. */
@@ -82,7 +85,7 @@ struct hpdata_s {
 	fb_group_t touched_pages[FB_NGROUPS(HUGEPAGE_PAGES)];
 };
 
-TYPED_LIST(hpdata_list, hpdata_t, ql_link)
+TYPED_LIST(hpdata_empty_list, hpdata_t, ql_link_empty)
 typedef ph(hpdata_t) hpdata_age_heap_t;
 ph_proto(, hpdata_age_heap_, hpdata_age_heap_t, hpdata_t);
 
@@ -138,6 +141,17 @@ hpdata_updating_set(hpdata_t *hpdata, bool updating) {
 	hpdata->h_updating = updating;
 }
 
+static inline bool
+hpdata_in_psset_get(const hpdata_t *hpdata) {
+	return hpdata->h_in_psset;
+}
+
+static inline void
+hpdata_in_psset_set(hpdata_t *hpdata, bool in_psset) {
+	assert(in_psset != hpdata->h_in_psset);
+	hpdata->h_in_psset = in_psset;
+}
+
 static inline size_t
 hpdata_longest_free_range_get(const hpdata_t *hpdata) {
 	return hpdata->h_longest_free_range;
@@ -208,6 +222,11 @@ hpdata_empty(hpdata_t *hpdata) {
 	return hpdata->h_nactive == 0;
 }
 
+static inline bool
+hpdata_full(hpdata_t *hpdata) {
+	return hpdata->h_nactive == HUGEPAGE_PAGES;
+}
+
 void hpdata_init(hpdata_t *hpdata, void *addr, uint64_t age);
 
 /*

include/jemalloc/internal/psset.h

@@ -35,7 +35,6 @@ struct psset_bin_stats_s {
 
 typedef struct psset_stats_s psset_stats_t;
 struct psset_stats_s {
-
 	/*
 	 * The second index is huge stats; nonfull_slabs[pszind][0] contains
 	 * stats for the non-huge slabs in bucket pszind, while
@@ -44,10 +43,13 @@ struct psset_stats_s {
 	psset_bin_stats_t nonfull_slabs[PSSET_NPSIZES][2];
 
 	/*
-	 * Full slabs don't live in any edata heap.  But we still track their
+	 * Full slabs don't live in any edata heap, but we still track their
 	 * stats.
 	 */
 	psset_bin_stats_t full_slabs[2];
+
+	/* Empty slabs are similar. */
+	psset_bin_stats_t empty_slabs[2];
 };
 
 typedef struct psset_s psset_t;
@@ -59,6 +61,8 @@ struct psset_s {
 	hpdata_age_heap_t pageslabs[PSSET_NPSIZES];
 	bitmap_t bitmap[BITMAP_GROUPS(PSSET_NPSIZES)];
 	psset_stats_t stats;
+	/* Slabs with no active allocations. */
+	hpdata_empty_list_t empty_slabs;
 };
 
 void psset_init(psset_t *psset);
@@ -74,4 +78,7 @@ void psset_update_end(psset_t *psset, hpdata_t *ps);
 /* Analogous to the eset_fit; pick a hpdata to serve the request. */
 hpdata_t *psset_pick_alloc(psset_t *psset, size_t size);
 
+void psset_insert(psset_t *psset, hpdata_t *ps);
+void psset_remove(psset_t *psset, hpdata_t *ps);
+
 #endif /* JEMALLOC_INTERNAL_PSSET_H */

src/ctl.c

@@ -226,7 +226,6 @@ 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_npurge_passes)
 CTL_PROTO(stats_arenas_i_hpa_shard_npurges)
 CTL_PROTO(stats_arenas_i_hpa_shard_nhugifies)
@@ -700,7 +699,6 @@ static const ctl_named_node_t stats_arenas_i_hpa_shard_node[] = {
 	{NAME("nonfull_slabs"),	CHILD(indexed,
 	    stats_arenas_i_hpa_shard_nonfull_slabs)},
 
-	{NAME("nevictions"),	CTL(stats_arenas_i_hpa_shard_nevictions)},
 	{NAME("npurge_passes"),	CTL(stats_arenas_i_hpa_shard_npurge_passes)},
 	{NAME("npurges"),	CTL(stats_arenas_i_hpa_shard_npurges)},
 	{NAME("nhugifies"),	CTL(stats_arenas_i_hpa_shard_nhugifies)},
@@ -3514,8 +3512,6 @@ 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.nonderived_stats.nevictions, uint64_t);
 CTL_RO_CGEN(config_stats, stats_arenas_i_hpa_shard_npurge_passes,
     arenas_i(mib[2])->astats->hpastats.nonderived_stats.npurge_passes, uint64_t);
 CTL_RO_CGEN(config_stats, stats_arenas_i_hpa_shard_npurges,

src/hpa.c

@@ -68,14 +68,12 @@ hpa_shard_init(hpa_shard_t *shard, emap_t *emap, base_t *base,
 	edata_cache_small_init(&shard->ecs, edata_cache);
 	psset_init(&shard->psset);
 	shard->alloc_max = alloc_max;
-	hpdata_list_init(&shard->unused_slabs);
 	shard->age_counter = 0;
 	shard->eden = NULL;
 	shard->eden_len = 0;
 	shard->ind = ind;
 	shard->emap = emap;
 
-	shard->stats.nevictions = 0;
 	shard->stats.npurge_passes = 0;
 	shard->stats.npurges = 0;
 	shard->stats.nhugifies = 0;
@@ -103,7 +101,6 @@ hpa_shard_init(hpa_shard_t *shard, emap_t *emap, base_t *base,
 static void
 hpa_shard_nonderived_stats_accum(hpa_shard_nonderived_stats_t *dst,
     hpa_shard_nonderived_stats_t *src) {
-	dst->nevictions += src->nevictions;
 	dst->npurge_passes += src->npurge_passes;
 	dst->npurges += src->npurges;
 	dst->nhugifies += src->nhugifies;
@@ -171,15 +168,6 @@ hpa_grow(tsdn_t *tsdn, hpa_shard_t *shard) {
 	malloc_mutex_assert_owner(tsdn, &shard->grow_mtx);
 	hpdata_t *ps = NULL;
 
-	/* Is there address space waiting for reuse? */
-	malloc_mutex_assert_owner(tsdn, &shard->grow_mtx);
-	ps = hpdata_list_first(&shard->unused_slabs);
-	if (ps != NULL) {
-		hpdata_list_remove(&shard->unused_slabs, ps);
-		hpdata_age_set(ps, shard->age_counter++);
-		return ps;
-	}
-
 	/* Is eden a perfect fit? */
 	if (shard->eden != NULL && shard->eden_len == HUGEPAGE) {
 		ps = hpa_alloc_ps(tsdn, shard);
@@ -300,26 +288,6 @@ hpa_purge(tsdn_t *tsdn, hpa_shard_t *shard, hpdata_t *ps) {
 	}
 }
 
-/*
- * Does the metadata tracking associated with a page slab becoming empty.  The
- * psset doesn't hold empty pageslabs, but we do want address space reuse, so we
- * track these pages outside the psset.
- */
-static void
-hpa_handle_ps_eviction(tsdn_t *tsdn, hpa_shard_t *shard, hpdata_t *ps) {
-	/*
-	 * We do relatively expensive system calls.  The ps was evicted, so no
-	 * one should touch it while we're also touching it.
-	 */
-	malloc_mutex_assert_not_owner(tsdn, &shard->mtx);
-	malloc_mutex_assert_not_owner(tsdn, &shard->grow_mtx);
-
-	malloc_mutex_lock(tsdn, &shard->grow_mtx);
-	shard->stats.nevictions++;
-	hpdata_list_prepend(&shard->unused_slabs, ps);
-	malloc_mutex_unlock(tsdn, &shard->grow_mtx);
-}
-
 static edata_t *
 hpa_try_alloc_no_grow(tsdn_t *tsdn, hpa_shard_t *shard, size_t size, bool *oom) {
 	bool err;
@@ -341,6 +309,18 @@ hpa_try_alloc_no_grow(tsdn_t *tsdn, hpa_shard_t *shard, size_t size, bool *oom)
 	}
 
 	psset_update_begin(&shard->psset, ps);
+
+	if (hpdata_empty(ps)) {
+		/*
+		 * If the pageslab used to be empty, treat it as though it's
+		 * brand new for fragmentation-avoidance purposes; what we're
+		 * trying to approximate is the age of the allocations *in* that
+		 * pageslab, and the allocations in the new pageslab are
+		 * definitionally the youngest in this hpa shard.
+		 */
+		hpdata_age_set(ps, shard->age_counter++);
+	}
+
 	void *addr = hpdata_reserve_alloc(ps, size);
 	edata_init(edata, shard->ind, addr, size, /* slab */ false,
 	    SC_NSIZES, /* sn */ 0, extent_state_active, /* zeroed */ false,
@@ -453,26 +433,20 @@ hpa_alloc_psset(tsdn_t *tsdn, hpa_shard_t *shard, size_t size) {
 		return NULL;
 	}
 
-	/* We got the new edata; allocate from it. */
+	/* We got the pageslab; allocate from it. */
 	malloc_mutex_lock(tsdn, &shard->mtx);
-	/*
+
-	 * This will go away soon.  The psset doesn't draw a distinction between
+	psset_insert(&shard->psset, ps);
-	 * pageslab removal and updating.  If this is a new pageslab, we pretend
-	 * that it's an old one that's been getting updated.
-	 */
-	if (!hpdata_updating_get(ps)) {
-		hpdata_updating_set(ps, true);
-	}
 
 	edata = edata_cache_small_get(tsdn, &shard->ecs);
 	if (edata == NULL) {
-		shard->stats.nevictions++;
 		malloc_mutex_unlock(tsdn, &shard->mtx);
 		malloc_mutex_unlock(tsdn, &shard->grow_mtx);
-		hpa_handle_ps_eviction(tsdn, shard, ps);
 		return NULL;
 	}
 
+	psset_update_begin(&shard->psset, ps);
+
 	void *addr = hpdata_reserve_alloc(ps, size);
 	edata_init(edata, shard->ind, addr, size, /* slab */ false,
 	    SC_NSIZES, /* sn */ 0, extent_state_active, /* zeroed */ false,
@@ -487,10 +461,6 @@ hpa_alloc_psset(tsdn_t *tsdn, hpa_shard_t *shard, size_t size) {
 
 		edata_cache_small_put(tsdn, &shard->ecs, edata);
 
-		shard->stats.nevictions++;
-		malloc_mutex_unlock(tsdn, &shard->mtx);
-		malloc_mutex_unlock(tsdn, &shard->grow_mtx);
-
 		/* We'll do a fake purge; the pages weren't really touched. */
 		hpdata_purge_state_t purge_state;
 		void *purge_addr;
@@ -506,7 +476,9 @@ hpa_alloc_psset(tsdn_t *tsdn, hpa_shard_t *shard, size_t size) {
 		assert(!found_extent);
 		hpdata_purge_end(ps, &purge_state);
 
-		hpa_handle_ps_eviction(tsdn, shard, ps);
+		psset_update_end(&shard->psset, ps);
+		malloc_mutex_unlock(tsdn, &shard->mtx);
+		malloc_mutex_unlock(tsdn, &shard->grow_mtx);
 		return NULL;
 	}
 	psset_update_end(&shard->psset, ps);
@@ -614,9 +586,7 @@ hpa_dalloc(tsdn_t *tsdn, pai_t *self, edata_t *edata) {
 	 *   management.
 	 * - The ps must not be in the psset while purging.  This is because we
 	 *   can't handle purge/alloc races.
-	 * - Whoever removes the ps from the psset is the one to reinsert it (or
+	 * - Whoever removes the ps from the psset is the one to reinsert it.
-	 *   to pass it to hpa_handle_ps_eviction upon emptying).  This keeps
-	 *   responsibility tracking simple.
 	 */
 	if (hpdata_mid_purge_get(ps)) {
 		/*
@@ -649,18 +619,10 @@ hpa_dalloc(tsdn_t *tsdn, pai_t *self, edata_t *edata) {
 	/* It's our job to purge. */
 	hpa_purge(tsdn, shard, ps);
 
-	/*
-	 * OK, the hpdata is as purged as we want it to be, and it's going back
-	 * into the psset (if nonempty) or getting evicted (if empty).
-	 */
-	if (hpdata_empty(ps)) {
-		malloc_mutex_unlock(tsdn, &shard->mtx);
-		hpa_handle_ps_eviction(tsdn, shard, ps);
-	} else {
 	psset_update_end(&shard->psset, ps);
+
 	malloc_mutex_unlock(tsdn, &shard->mtx);
 }
-}
 
 void
 hpa_shard_disable(tsdn_t *tsdn, hpa_shard_t *shard) {
@@ -678,8 +640,6 @@ hpa_shard_assert_stats_empty(psset_bin_stats_t *bin_stats) {
 static void
 hpa_assert_empty(tsdn_t *tsdn, hpa_shard_t *shard, psset_t *psset) {
 	malloc_mutex_assert_owner(tsdn, &shard->mtx);
-	hpdata_t *ps = psset_pick_alloc(psset, PAGE);
-	assert(ps == NULL);
 	for (int huge = 0; huge <= 1; huge++) {
 		hpa_shard_assert_stats_empty(&psset->stats.full_slabs[huge]);
 		for (pszind_t i = 0; i < PSSET_NPSIZES; i++) {
@@ -703,8 +663,10 @@ hpa_shard_destroy(tsdn_t *tsdn, hpa_shard_t *shard) {
 		malloc_mutex_unlock(tsdn, &shard->mtx);
 	}
 	hpdata_t *ps;
-	while ((ps = hpdata_list_first(&shard->unused_slabs)) != NULL) {
+	while ((ps = psset_pick_alloc(&shard->psset, PAGE)) != NULL) {
-		hpdata_list_remove(&shard->unused_slabs, ps);
+		/* There should be no allocations anywhere. */
+		assert(hpdata_empty(ps));
+		psset_remove(&shard->psset, ps);
 		pages_unmap(hpdata_addr_get(ps), HUGEPAGE);
 	}
 }

src/hpdata.c

@@ -25,6 +25,7 @@ hpdata_init(hpdata_t *hpdata, void *addr, uint64_t age) {
 	hpdata->h_mid_purge = false;
 	hpdata->h_mid_hugify = false;
 	hpdata->h_updating = false;
+	hpdata->h_in_psset = false;
 	hpdata_longest_free_range_set(hpdata, HUGEPAGE_PAGES);
 	hpdata->h_nactive = 0;
 	fb_init(hpdata->active_pages, HUGEPAGE_PAGES);
@@ -37,7 +38,12 @@ hpdata_init(hpdata_t *hpdata, void *addr, uint64_t age) {
 void *
 hpdata_reserve_alloc(hpdata_t *hpdata, size_t sz) {
 	hpdata_assert_consistent(hpdata);
-	assert(hpdata->h_updating);
+	/*
+	 * This is a metadata change; the hpdata should therefore either not be
+	 * in the psset, or should have explicitly marked itself as being
+	 * mid-update.
+	 */
+	assert(!hpdata->h_in_psset || hpdata->h_updating);
 	assert((sz & PAGE_MASK) == 0);
 	size_t npages = sz >> LG_PAGE;
 	assert(npages <= hpdata_longest_free_range_get(hpdata));
@@ -118,7 +124,8 @@ hpdata_reserve_alloc(hpdata_t *hpdata, size_t sz) {
 void
 hpdata_unreserve(hpdata_t *hpdata, void *addr, size_t sz) {
 	hpdata_assert_consistent(hpdata);
-	assert(hpdata->h_updating);
+	/* See the comment in reserve. */
+	assert(!hpdata->h_in_psset || hpdata->h_updating);
 	assert(((uintptr_t)addr & PAGE_MASK) == 0);
 	assert((sz & PAGE_MASK) == 0);
 	size_t begin = ((uintptr_t)addr - (uintptr_t)hpdata_addr_get(hpdata))
@@ -147,7 +154,8 @@ hpdata_unreserve(hpdata_t *hpdata, void *addr, size_t sz) {
 void
 hpdata_purge_begin(hpdata_t *hpdata, hpdata_purge_state_t *purge_state) {
 	hpdata_assert_consistent(hpdata);
-	assert(hpdata->h_updating);
+	/* See the comment in reserve. */
+	assert(!hpdata->h_in_psset || hpdata->h_updating);
 	assert(!hpdata->h_mid_purge);
 	assert(!hpdata->h_mid_hugify);
 	hpdata->h_mid_purge = true;
@@ -185,7 +193,8 @@ hpdata_purge_next(hpdata_t *hpdata, hpdata_purge_state_t *purge_state,
 	 * a consistent state.
 	 */
 	assert(hpdata->h_mid_purge);
-	assert(hpdata->h_updating);
+	/* See the comment in reserve. */
+	assert(!hpdata->h_in_psset || hpdata->h_updating);
 	/* Should have dehugified already (if necessary). */
 	assert(!hpdata->h_huge);
 	assert(!hpdata->h_mid_hugify);
@@ -215,7 +224,8 @@ hpdata_purge_next(hpdata_t *hpdata, hpdata_purge_state_t *purge_state,
 void
 hpdata_purge_end(hpdata_t *hpdata, hpdata_purge_state_t *purge_state) {
 	hpdata_assert_consistent(hpdata);
-	assert(hpdata->h_updating);
+	/* See the comment in reserve. */
+	assert(!hpdata->h_in_psset || hpdata->h_updating);
 	assert(hpdata->h_mid_purge);
 	assert(!hpdata->h_mid_hugify);
 	hpdata->h_mid_purge = false;
@@ -236,7 +246,8 @@ hpdata_purge_end(hpdata_t *hpdata, hpdata_purge_state_t *purge_state) {
 void
 hpdata_hugify_begin(hpdata_t *hpdata) {
 	hpdata_assert_consistent(hpdata);
-	assert(hpdata->h_updating);
+	/* See the comment in reserve. */
+	assert(!hpdata->h_in_psset || hpdata->h_updating);
 	assert(!hpdata->h_mid_purge);
 	assert(!hpdata->h_mid_hugify);
 	hpdata->h_mid_hugify = true;
@@ -253,7 +264,7 @@ hpdata_hugify_end(hpdata_t *hpdata) {
 	 * This is the exception to the "no-metadata updates without informing
 	 * the psset first" rule; this assert would be incorrect.
 	 */
-	/* assert(hpdata->h_updating); */
+	/* assert(!hpdata->h_in_psset || hpdata->h_updating); */
 	assert(!hpdata->h_mid_purge);
 	assert(hpdata->h_mid_hugify);
 	hpdata->h_mid_hugify = false;

src/psset.c

@@ -15,6 +15,7 @@ psset_init(psset_t *psset) {
 	}
 	bitmap_init(psset->bitmap, &psset_bitmap_info, /* fill */ true);
 	memset(&psset->stats, 0, sizeof(psset->stats));
+	hpdata_empty_list_init(&psset->empty_slabs);
 }
 
 static void
@@ -28,6 +29,8 @@ void
 psset_stats_accum(psset_stats_t *dst, psset_stats_t *src) {
 	psset_bin_stats_accum(&dst->full_slabs[0], &src->full_slabs[0]);
 	psset_bin_stats_accum(&dst->full_slabs[1], &src->full_slabs[1]);
+	psset_bin_stats_accum(&dst->empty_slabs[0], &src->empty_slabs[0]);
+	psset_bin_stats_accum(&dst->empty_slabs[1], &src->empty_slabs[1]);
 	for (pszind_t i = 0; i < PSSET_NPSIZES; i++) {
 		psset_bin_stats_accum(&dst->nonfull_slabs[i][0],
 		    &src->nonfull_slabs[i][0]);
@@ -69,71 +72,104 @@ psset_bin_stats_remove(psset_bin_stats_t *binstats, hpdata_t *ps) {
 static void
 psset_hpdata_heap_remove(psset_t *psset, pszind_t pind, hpdata_t *ps) {
 	hpdata_age_heap_remove(&psset->pageslabs[pind], ps);
-	psset_bin_stats_remove(psset->stats.nonfull_slabs[pind], ps);
-}
-
-static void
-psset_hpdata_heap_insert(psset_t *psset, pszind_t pind, hpdata_t *ps) {
-	hpdata_age_heap_insert(&psset->pageslabs[pind], ps);
-	psset_bin_stats_insert(psset->stats.nonfull_slabs[pind], ps);
-}
-
-void
-psset_update_begin(psset_t *psset, hpdata_t *ps) {
-	hpdata_assert_consistent(ps);
-	assert(!hpdata_updating_get(ps));
-	hpdata_updating_set(ps, true);
-
-	size_t longest_free_range = hpdata_longest_free_range_get(ps);
-
-	if (longest_free_range == 0) {
-		psset_bin_stats_remove(psset->stats.full_slabs, ps);
-		return;
-	}
-
-	pszind_t pind = sz_psz2ind(sz_psz_quantize_floor(
-	    longest_free_range << LG_PAGE));
-	assert(pind < PSSET_NPSIZES);
-	psset_hpdata_heap_remove(psset, pind, ps);
 	if (hpdata_age_heap_empty(&psset->pageslabs[pind])) {
 		bitmap_set(psset->bitmap, &psset_bitmap_info, (size_t)pind);
 	}
 }
 
-void
+static void
-psset_update_end(psset_t *psset, hpdata_t *ps) {
+psset_hpdata_heap_insert(psset_t *psset, pszind_t pind, hpdata_t *ps) {
-	assert(!hpdata_empty(ps));
-	hpdata_assert_consistent(ps);
-	assert(hpdata_updating_get(ps));
-	hpdata_updating_set(ps, false);
-	size_t longest_free_range = hpdata_longest_free_range_get(ps);
-
-	if (longest_free_range == 0) {
-		/*
-		 * We don't ned to track full slabs; just pretend to for stats
-		 * purposes.  See the comment at psset_bin_stats_adjust.
-		 */
-		psset_bin_stats_insert(psset->stats.full_slabs, ps);
-		return;
-	}
-
-	pszind_t pind = sz_psz2ind(sz_psz_quantize_floor(
-	    longest_free_range << LG_PAGE));
-
-	assert(pind < PSSET_NPSIZES);
 	if (hpdata_age_heap_empty(&psset->pageslabs[pind])) {
 		bitmap_unset(psset->bitmap, &psset_bitmap_info, (size_t)pind);
 	}
+	hpdata_age_heap_insert(&psset->pageslabs[pind], ps);
+}
+
+/*
+ * Insert ps into the data structures we use to track allocation stats and pick
+ * the pageslabs for new allocations.
+ *
+ * In particular, this does *not* remove ps from any hugification / purging
+ * queues it may be in.
+ */
+static void
+psset_do_alloc_tracking_insert(psset_t *psset, hpdata_t *ps) {
+	if (hpdata_empty(ps)) {
+		psset_bin_stats_insert(psset->stats.empty_slabs, ps);
+		/*
+		 * This prepend, paired with popping the head in psset_fit,
+		 * means we implement LIFO ordering for the empty slabs set,
+		 * which seems reasonable.
+		 */
+		hpdata_empty_list_prepend(&psset->empty_slabs, ps);
+	} else if (hpdata_full(ps)) {
+		psset_bin_stats_insert(psset->stats.full_slabs, ps);
+		/*
+		 * We don't need to keep track of the full slabs; we're never
+		 * going to return them from a psset_pick_alloc call.
+		 */
+	} else {
+		size_t longest_free_range = hpdata_longest_free_range_get(ps);
+
+		pszind_t pind = sz_psz2ind(sz_psz_quantize_floor(
+		    longest_free_range << LG_PAGE));
+		assert(pind < PSSET_NPSIZES);
+
+		psset_bin_stats_insert(psset->stats.nonfull_slabs[pind], ps);
 		psset_hpdata_heap_insert(psset, pind, ps);
 	}
+}
+
+/* Remove ps from those collections. */
+static void
+psset_do_alloc_tracking_remove(psset_t *psset, hpdata_t *ps) {
+	if (hpdata_empty(ps)) {
+		psset_bin_stats_remove(psset->stats.empty_slabs, ps);
+		hpdata_empty_list_remove(&psset->empty_slabs, ps);
+	} else if (hpdata_full(ps)) {
+		/*
+		 * We don't need to maintain an explicit container of full
+		 * pageslabs anywhere, but we do have to update stats.
+		 */
+		psset_bin_stats_remove(psset->stats.full_slabs, ps);
+	} else {
+		size_t longest_free_range = hpdata_longest_free_range_get(ps);
+
+		pszind_t pind = sz_psz2ind(sz_psz_quantize_floor(
+		    longest_free_range << LG_PAGE));
+		assert(pind < PSSET_NPSIZES);
+
+		psset_bin_stats_remove(psset->stats.nonfull_slabs[pind], ps);
+		psset_hpdata_heap_remove(psset, pind, ps);
+	}
+}
+
+void
+psset_update_begin(psset_t *psset, hpdata_t *ps) {
+	hpdata_assert_consistent(ps);
+	assert(hpdata_in_psset_get(ps));
+	hpdata_updating_set(ps, true);
+	psset_do_alloc_tracking_remove(psset, ps);
+}
+
+void
+psset_update_end(psset_t *psset, hpdata_t *ps) {
+	hpdata_assert_consistent(ps);
+	assert(hpdata_in_psset_get(ps));
+	hpdata_updating_set(ps, false);
+	psset_do_alloc_tracking_insert(psset, ps);
+}
 
 hpdata_t *
 psset_pick_alloc(psset_t *psset, size_t size) {
+	assert((size & PAGE_MASK) == 0);
+	assert(size <= HUGEPAGE);
+
 	pszind_t min_pind = sz_psz2ind(sz_psz_quantize_ceil(size));
 	pszind_t pind = (pszind_t)bitmap_ffu(psset->bitmap, &psset_bitmap_info,
 	    (size_t)min_pind);
 	if (pind == PSSET_NPSIZES) {
-		return NULL;
+		return hpdata_empty_list_first(&psset->empty_slabs);
 	}
 	hpdata_t *ps = hpdata_age_heap_first(&psset->pageslabs[pind]);
 	if (ps == NULL) {
@@ -144,3 +180,17 @@ psset_pick_alloc(psset_t *psset, size_t size) {
 
 	return ps;
 }
+
+void
+psset_insert(psset_t *psset, hpdata_t *ps) {
+	/* We only support inserting empty pageslabs, for now. */
+	assert(hpdata_empty(ps));
+	hpdata_in_psset_set(ps, true);
+	psset_do_alloc_tracking_insert(psset, ps);
+}
+
+void
+psset_remove(psset_t *psset, hpdata_t *ps) {
+	hpdata_in_psset_set(ps, false);
+	psset_do_alloc_tracking_remove(psset, ps);
+}

src/stats.c

@@ -790,14 +790,11 @@ stats_arena_hpa_shard_print(emitter_t *emitter, unsigned i, uint64_t uptime) {
 	emitter_row_t row;
 	emitter_row_init(&row);
 
-	uint64_t nevictions;
 	uint64_t npurge_passes;
 	uint64_t npurges;
 	uint64_t nhugifies;
 	uint64_t ndehugifies;
 
-	CTL_M2_GET("stats.arenas.0.hpa_shard.nevictions",
-	    i, &nevictions, uint64_t);
 	CTL_M2_GET("stats.arenas.0.hpa_shard.npurge_passes",
 	    i, &npurge_passes, uint64_t);
 	CTL_M2_GET("stats.arenas.0.hpa_shard.npurges",
@@ -839,7 +836,6 @@ stats_arena_hpa_shard_print(emitter_t *emitter, unsigned i, uint64_t uptime) {
 
 	emitter_table_printf(emitter,
 	    "HPA shard stats:\n"
-	    "  Evictions: %" FMTu64 " (%" FMTu64 " / sec)\n"
 	    "  Purge passes: %" FMTu64 " (%" FMTu64 " / sec)\n"
 	    "  Purges: %" FMTu64 " (%" FMTu64 " / sec)\n"
 	    "  Hugeifies: %" FMTu64 " (%" FMTu64 " / sec)\n"
@@ -850,7 +846,6 @@ stats_arena_hpa_shard_print(emitter_t *emitter, unsigned i, uint64_t uptime) {
 	    "      nactive: %zu huge, %zu nonhuge \n"
 	    "      ndirty: %zu huge, %zu nonhuge \n"
 	    "      nretained: 0 huge, %zu nonhuge \n",
-	    nevictions, rate_per_second(nevictions, uptime),
 	    npurge_passes, rate_per_second(npurge_passes, uptime),
 	    npurges, rate_per_second(npurges, uptime),
 	    nhugifies, rate_per_second(nhugifies, uptime),
@@ -861,8 +856,6 @@ stats_arena_hpa_shard_print(emitter_t *emitter, unsigned i, uint64_t uptime) {
 	    nretained_nonhuge);
 
 	emitter_json_object_kv_begin(emitter, "hpa_shard");
-	emitter_json_kv(emitter, "nevictions", emitter_type_uint64,
-	    &nevictions);
 	emitter_json_kv(emitter, "npurge_passes", emitter_type_uint64,
 	    &npurge_passes);
 	emitter_json_kv(emitter, "npurges", emitter_type_uint64,

test/unit/hpdata.c

@@ -7,8 +7,6 @@ TEST_BEGIN(test_reserve_alloc) {
 	hpdata_t hpdata;
 	hpdata_init(&hpdata, HPDATA_ADDR, HPDATA_AGE);
 
-	hpdata_updating_set(&hpdata, true);
-
 	/* Allocating a page at a time, we should do first fit. */
 	for (size_t i = 0; i < HUGEPAGE_PAGES; i++) {
 		expect_true(hpdata_consistent(&hpdata), "");
@@ -61,8 +59,6 @@ TEST_BEGIN(test_purge_simple) {
 	hpdata_t hpdata;
 	hpdata_init(&hpdata, HPDATA_ADDR, HPDATA_AGE);
 
-	hpdata_updating_set(&hpdata, true);
-
 	void *alloc = hpdata_reserve_alloc(&hpdata, HUGEPAGE_PAGES / 2 * PAGE);
 	expect_ptr_eq(alloc, HPDATA_ADDR, "");
 
@@ -111,7 +107,6 @@ TEST_END
 TEST_BEGIN(test_purge_intervening_dalloc) {
 	hpdata_t hpdata;
 	hpdata_init(&hpdata, HPDATA_ADDR, HPDATA_AGE);
-	hpdata_updating_set(&hpdata, true);
 
 	/* Allocate the first 3/4 of the pages. */
 	void *alloc = hpdata_reserve_alloc(&hpdata, 3 * HUGEPAGE_PAGES / 4  * PAGE);
@@ -165,7 +160,6 @@ TEST_END
 TEST_BEGIN(test_hugify) {
 	hpdata_t hpdata;
 	hpdata_init(&hpdata, HPDATA_ADDR, HPDATA_AGE);
-	hpdata_updating_set(&hpdata, true);
 
 	void *alloc = hpdata_reserve_alloc(&hpdata, HUGEPAGE / 2);
 	expect_ptr_eq(alloc, HPDATA_ADDR, "");

test/unit/psset.c

@@ -15,18 +15,26 @@ edata_init_test(edata_t *edata) {
 	edata_esn_set(edata, ALLOC_ESN);
 }
 
+static void
+test_psset_fake_purge(hpdata_t *ps) {
+	hpdata_purge_state_t purge_state;
+	hpdata_purge_begin(ps, &purge_state);
+	void *addr;
+	size_t size;
+	while (hpdata_purge_next(ps, &purge_state, &addr, &size)) {
+	}
+	hpdata_purge_end(ps, &purge_state);
+}
+
 static void
 test_psset_alloc_new(psset_t *psset, hpdata_t *ps, edata_t *r_edata,
     size_t size) {
 	hpdata_assert_empty(ps);
 
-	/*
+	test_psset_fake_purge(ps);
-	 * As in hpa.c; pretend that the ps is already in the psset and just
+
-	 * being updated, until we implement true insert/removal support.
+	psset_insert(psset, ps);
-	 */
+	psset_update_begin(psset, ps);
-	if (!hpdata_updating_get(ps)) {
-		hpdata_updating_set(ps, true);
-	}
 
         void *addr = hpdata_reserve_alloc(ps, size);
         edata_init(r_edata, edata_arena_ind_get(r_edata), addr, size,
@@ -59,10 +67,11 @@ test_psset_dalloc(psset_t *psset, edata_t *edata) {
 	hpdata_t *ps = edata_ps_get(edata);
 	psset_update_begin(psset, ps);
 	hpdata_unreserve(ps, edata_addr_get(edata), edata_size_get(edata));
+	psset_update_end(psset, ps);
 	if (hpdata_empty(ps)) {
+		psset_remove(psset, ps);
 		return ps;
 	} else {
-		psset_update_end(psset, ps);
 		return NULL;
 	}
 }