1 files changed, 269 insertions, 52 deletions

diff --git a/net/rds/ib_recv.c b/net/rds/ib_recv.c
index 48add10..5b429b7 100644
--- a/net/rds/ib_recv.c
+++ b/net/rds/ib_recv.c
@@ -43,14 +43,6 @@ static struct kmem_cache *rds_ib_incoming_slab;
 static struct kmem_cache *rds_ib_frag_slab;
 static atomic_t	rds_ib_allocation = ATOMIC_INIT(0);
 
-/* Free frag and attached recv buffer f_sg */
-static void rds_ib_frag_free(struct rds_page_frag *frag)
-{
-	rdsdebug("frag %p page %p\n", frag, sg_page(&frag->f_sg));
-	__free_page(sg_page(&frag->f_sg));
-	kmem_cache_free(rds_ib_frag_slab, frag);
-}
-
 void rds_ib_recv_init_ring(struct rds_ib_connection *ic)
 {
 	struct rds_ib_recv_work *recv;
@@ -79,6 +71,151 @@ void rds_ib_recv_init_ring(struct rds_ib_connection *ic)
 	}
 }
 
+/*
+ * The entire 'from' list, including the from element itself, is put on
+ * to the tail of the 'to' list.
+ */
+static void list_splice_entire_tail(struct list_head *from,
+				    struct list_head *to)
+{
+	struct list_head *from_last = from->prev;
+
+	list_splice_tail(from_last, to);
+	list_add_tail(from_last, to);
+}
+
+static void rds_ib_cache_xfer_to_ready(struct rds_ib_refill_cache *cache)
+{
+	struct list_head *tmp;
+
+	tmp = xchg(&cache->xfer, NULL);
+	if (tmp) {
+		if (cache->ready)
+			list_splice_entire_tail(tmp, cache->ready);
+		else
+			cache->ready = tmp;
+	}
+}
+
+static int rds_ib_recv_alloc_cache(struct rds_ib_refill_cache *cache)
+{
+	struct rds_ib_cache_head *head;
+	int cpu;
+
+	cache->percpu = alloc_percpu(struct rds_ib_cache_head);
+	if (!cache->percpu)
+	       return -ENOMEM;
+
+	for_each_possible_cpu(cpu) {
+		head = per_cpu_ptr(cache->percpu, cpu);
+		head->first = NULL;
+		head->count = 0;
+	}
+	cache->xfer = NULL;
+	cache->ready = NULL;
+
+	return 0;
+}
+
+int rds_ib_recv_alloc_caches(struct rds_ib_connection *ic)
+{
+	int ret;
+
+	ret = rds_ib_recv_alloc_cache(&ic->i_cache_incs);
+	if (!ret) {
+		ret = rds_ib_recv_alloc_cache(&ic->i_cache_frags);
+		if (ret)
+			free_percpu(ic->i_cache_incs.percpu);
+	}
+
+	return ret;
+}
+
+static void rds_ib_cache_splice_all_lists(struct rds_ib_refill_cache *cache,
+					  struct list_head *caller_list)
+{
+	struct rds_ib_cache_head *head;
+	int cpu;
+
+	for_each_possible_cpu(cpu) {
+		head = per_cpu_ptr(cache->percpu, cpu);
+		if (head->first) {
+			list_splice_entire_tail(head->first, caller_list);
+			head->first = NULL;
+		}
+	}
+
+	if (cache->ready) {
+		list_splice_entire_tail(cache->ready, caller_list);
+		cache->ready = NULL;
+	}
+}
+
+void rds_ib_recv_free_caches(struct rds_ib_connection *ic)
+{
+	struct rds_ib_incoming *inc;
+	struct rds_ib_incoming *inc_tmp;
+	struct rds_page_frag *frag;
+	struct rds_page_frag *frag_tmp;
+	LIST_HEAD(list);
+
+	rds_ib_cache_xfer_to_ready(&ic->i_cache_incs);
+	rds_ib_cache_splice_all_lists(&ic->i_cache_incs, &list);
+	free_percpu(ic->i_cache_incs.percpu);
+
+	list_for_each_entry_safe(inc, inc_tmp, &list, ii_cache_entry) {
+		list_del(&inc->ii_cache_entry);
+		WARN_ON(!list_empty(&inc->ii_frags));
+		kmem_cache_free(rds_ib_incoming_slab, inc);
+	}
+
+	rds_ib_cache_xfer_to_ready(&ic->i_cache_frags);
+	rds_ib_cache_splice_all_lists(&ic->i_cache_frags, &list);
+	free_percpu(ic->i_cache_frags.percpu);
+
+	list_for_each_entry_safe(frag, frag_tmp, &list, f_cache_entry) {
+		list_del(&frag->f_cache_entry);
+		WARN_ON(!list_empty(&frag->f_item));
+		kmem_cache_free(rds_ib_frag_slab, frag);
+	}
+}
+
+/* fwd decl */
+static void rds_ib_recv_cache_put(struct list_head *new_item,
+				  struct rds_ib_refill_cache *cache);
+static struct list_head *rds_ib_recv_cache_get(struct rds_ib_refill_cache *cache);
+
+
+/* Recycle frag and attached recv buffer f_sg */
+static void rds_ib_frag_free(struct rds_ib_connection *ic,
+			     struct rds_page_frag *frag)
+{
+	rdsdebug("frag %p page %p\n", frag, sg_page(&frag->f_sg));
+
+	rds_ib_recv_cache_put(&frag->f_cache_entry, &ic->i_cache_frags);
+}
+
+/* Recycle inc after freeing attached frags */
+void rds_ib_inc_free(struct rds_incoming *inc)
+{
+	struct rds_ib_incoming *ibinc;
+	struct rds_page_frag *frag;
+	struct rds_page_frag *pos;
+	struct rds_ib_connection *ic = inc->i_conn->c_transport_data;
+
+	ibinc = container_of(inc, struct rds_ib_incoming, ii_inc);
+
+	/* Free attached frags */
+	list_for_each_entry_safe(frag, pos, &ibinc->ii_frags, f_item) {
+		list_del_init(&frag->f_item);
+		rds_ib_frag_free(ic, frag);
+	}
+	BUG_ON(!list_empty(&ibinc->ii_frags));
+
+	rdsdebug("freeing ibinc %p inc %p\n", ibinc, inc);
+	rds_ib_recv_cache_put(&ibinc->ii_cache_entry, &ic->i_cache_incs);
+}
+
 static void rds_ib_recv_clear_one(struct rds_ib_connection *ic,
 				  struct rds_ib_recv_work *recv)
 {
@@ -88,7 +225,7 @@ static void rds_ib_recv_clear_one(struct rds_ib_connection *ic,
 	}
 	if (recv->r_frag) {
 		ib_dma_unmap_sg(ic->i_cm_id->device, &recv->r_frag->f_sg, 1, DMA_FROM_DEVICE);
-		rds_ib_frag_free(recv->r_frag);
+		rds_ib_frag_free(ic, recv->r_frag);
 		recv->r_frag = NULL;
 	}
 }
@@ -101,6 +238,61 @@ void rds_ib_recv_clear_ring(struct rds_ib_connection *ic)
 		rds_ib_recv_clear_one(ic, &ic->i_recvs[i]);
 }
 
+static struct rds_ib_incoming *rds_ib_refill_one_inc(struct rds_ib_connection *ic)
+{
+	struct rds_ib_incoming *ibinc;
+	struct list_head *cache_item;
+	int avail_allocs;
+
+	cache_item = rds_ib_recv_cache_get(&ic->i_cache_incs);
+	if (cache_item) {
+		ibinc = container_of(cache_item, struct rds_ib_incoming, ii_cache_entry);
+	} else {
+		avail_allocs = atomic_add_unless(&rds_ib_allocation,
+						 1, rds_ib_sysctl_max_recv_allocation);
+		if (!avail_allocs) {
+			rds_ib_stats_inc(s_ib_rx_alloc_limit);
+			return NULL;
+		}
+		ibinc = kmem_cache_alloc(rds_ib_incoming_slab, GFP_NOWAIT);
+		if (!ibinc) {
+			atomic_dec(&rds_ib_allocation);
+			return NULL;
+		}
+	}
+	INIT_LIST_HEAD(&ibinc->ii_frags);
+	rds_inc_init(&ibinc->ii_inc, ic->conn, ic->conn->c_faddr);
+
+	return ibinc;
+}
+
+static struct rds_page_frag *rds_ib_refill_one_frag(struct rds_ib_connection *ic)
+{
+	struct rds_page_frag *frag;
+	struct list_head *cache_item;
+	int ret;
+
+	cache_item = rds_ib_recv_cache_get(&ic->i_cache_frags);
+	if (cache_item) {
+		frag = container_of(cache_item, struct rds_page_frag, f_cache_entry);
+	} else {
+		frag = kmem_cache_alloc(rds_ib_frag_slab, GFP_NOWAIT);
+		if (!frag)
+			return NULL;
+
+		ret = rds_page_remainder_alloc(&frag->f_sg,
+					       RDS_FRAG_SIZE, GFP_NOWAIT);
+		if (ret) {
+			kmem_cache_free(rds_ib_frag_slab, frag);
+			return NULL;
+		}
+	}
+
+	INIT_LIST_HEAD(&frag->f_item);
+
+	return frag;
+}
+
 static int rds_ib_recv_refill_one(struct rds_connection *conn,
 				  struct rds_ib_recv_work *recv)
 {
@@ -108,37 +300,25 @@ static int rds_ib_recv_refill_one(struct rds_connection *conn,
 	struct ib_sge *sge;
 	int ret = -ENOMEM;
 
+	if (!ic->i_cache_incs.ready)
+		rds_ib_cache_xfer_to_ready(&ic->i_cache_incs);
+	if (!ic->i_cache_frags.ready)
+		rds_ib_cache_xfer_to_ready(&ic->i_cache_frags);
+
 	/*
 	 * ibinc was taken from recv if recv contained the start of a message.
 	 * recvs that were continuations will still have this allocated.
 	 */
 	if (!recv->r_ibinc) {
-		if (!atomic_add_unless(&rds_ib_allocation, 1, rds_ib_sysctl_max_recv_allocation)) {
-			rds_ib_stats_inc(s_ib_rx_alloc_limit);
-			goto out;
-		}
-		recv->r_ibinc = kmem_cache_alloc(rds_ib_incoming_slab, GFP_NOWAIT);
-		if (!recv->r_ibinc) {
-			atomic_dec(&rds_ib_allocation);
+		recv->r_ibinc = rds_ib_refill_one_inc(ic);
+		if (!recv->r_ibinc)
 			goto out;
-		}
-		INIT_LIST_HEAD(&recv->r_ibinc->ii_frags);
-		rds_inc_init(&recv->r_ibinc->ii_inc, conn, conn->c_faddr);
 	}
 
 	WARN_ON(recv->r_frag); /* leak! */
-	recv->r_frag = kmem_cache_alloc(rds_ib_frag_slab, GFP_NOWAIT);
+	recv->r_frag = rds_ib_refill_one_frag(ic);
 	if (!recv->r_frag)
 		goto out;
-	INIT_LIST_HEAD(&recv->r_frag->f_item);
-	sg_init_table(&recv->r_frag->f_sg, 1);
-	ret = rds_page_remainder_alloc(&recv->r_frag->f_sg,
-				       RDS_FRAG_SIZE, GFP_NOWAIT);
-	if (ret) {
-		kmem_cache_free(rds_ib_frag_slab, recv->r_frag);
-		recv->r_frag = NULL;
-		goto out;
-	}
 
 	ret = ib_dma_map_sg(ic->i_cm_id->device, &recv->r_frag->f_sg,
 			    1, DMA_FROM_DEVICE);
@@ -160,8 +340,7 @@ out:
 /*
  * This tries to allocate and post unused work requests after making sure that
  * they have all the allocations they need to queue received fragments into
- * sockets.  The i_recv_mutex is held here so that ring_alloc and _unalloc
- * pairs don't go unmatched.
+ * sockets.
  *
  * -1 is returned if posting fails due to temporary resource exhaustion.
  */
@@ -216,33 +395,71 @@ int rds_ib_recv_refill(struct rds_connection *conn, int prefill)
 	return ret;
 }
 
-static void rds_ib_inc_purge(struct rds_incoming *inc)
+/*
+ * We want to recycle several types of recv allocations, like incs and frags.
+ * To use this, the *_free() function passes in the ptr to a list_head within
+ * the recyclee, as well as the cache to put it on.
+ *
+ * First, we put the memory on a percpu list. When this reaches a certain size,
+ * We move it to an intermediate non-percpu list in a lockless manner, with some
+ * xchg/compxchg wizardry.
+ *
+ * N.B. Instead of a list_head as the anchor, we use a single pointer, which can
+ * be NULL and xchg'd. The list is actually empty when the pointer is NULL, and
+ * list_empty() will return true with one element is actually present.
+ */
+static void rds_ib_recv_cache_put(struct list_head *new_item,
+				 struct rds_ib_refill_cache *cache)
 {
-	struct rds_ib_incoming *ibinc;
-	struct rds_page_frag *frag;
-	struct rds_page_frag *pos;
+	unsigned long flags;
+	struct rds_ib_cache_head *chp;
+	struct list_head *old;
 
-	ibinc = container_of(inc, struct rds_ib_incoming, ii_inc);
-	rdsdebug("purging ibinc %p inc %p\n", ibinc, inc);
+	local_irq_save(flags);
 
-	list_for_each_entry_safe(frag, pos, &ibinc->ii_frags, f_item) {
-		list_del_init(&frag->f_item);
-		rds_ib_frag_free(frag);
-	}
+	chp = per_cpu_ptr(cache->percpu, smp_processor_id());
+	if (!chp->first)
+		INIT_LIST_HEAD(new_item);
+	else /* put on front */
+		list_add_tail(new_item, chp->first);
+	chp->first = new_item;
+	chp->count++;
+
+	if (chp->count < RDS_IB_RECYCLE_BATCH_COUNT)
+		goto end;
+
+	/*
+	 * Return our per-cpu first list to the cache's xfer by atomically
+	 * grabbing the current xfer list, appending it to our per-cpu list,
+	 * and then atomically returning that entire list back to the
+	 * cache's xfer list as long as it's still empty.
+	 */
+	do {
+		old = xchg(&cache->xfer, NULL);
+		if (old)
+			list_splice_entire_tail(old, chp->first);
+		old = cmpxchg(&cache->xfer, NULL, chp->first);
+	} while (old);
+
+	chp->first = NULL;
+	chp->count = 0;
+end:
+	local_irq_restore(flags);
 }
 
-void rds_ib_inc_free(struct rds_incoming *inc)
+static struct list_head *rds_ib_recv_cache_get(struct rds_ib_refill_cache *cache)
 {
-	struct rds_ib_incoming *ibinc;
-
-	ibinc = container_of(inc, struct rds_ib_incoming, ii_inc);
+	struct list_head *head = cache->ready;
+
+	if (head) {
+		if (!list_empty(head)) {
+			cache->ready = head->next;
+			list_del_init(head);
+		} else
+			cache->ready = NULL;
+	}
 
-	rds_ib_inc_purge(inc);
-	rdsdebug("freeing ibinc %p inc %p\n", ibinc, inc);
-	BUG_ON(!list_empty(&ibinc->ii_frags));
-	kmem_cache_free(rds_ib_incoming_slab, ibinc);
-	atomic_dec(&rds_ib_allocation);
-	BUG_ON(atomic_read(&rds_ib_allocation) < 0);
+	return head;
 }
 
 int rds_ib_inc_copy_to_user(struct rds_incoming *inc, struct iovec *first_iov,
@@ -647,7 +864,7 @@ static void rds_ib_process_recv(struct rds_connection *conn,
 		 *
 		 * FIXME: Fold this into the code path below.
 		 */
-		rds_ib_frag_free(recv->r_frag);
+		rds_ib_frag_free(ic, recv->r_frag);
 		recv->r_frag = NULL;
 		return;
 	}