mlx4_core: Roll back round robin bitmap allocation commit for CQs, SRQs, and MPTs

Commit f4ec9e95 "mlx4_core: Change bitmap allocator to work in round-robin fashion"
introduced round-robin allocation (via bitmap) for all resources which allocate
via a bitmap.

Round robin allocation is desirable for mcgs, counters, pd's, UARs, and xrcds.
These are simply numbers, with no involvement of ICM memory mapping.

Round robin is required for QPs, since we had a problem with immediate
reuse of a 24-bit QP number (commit f4ec9e95).

However, for other resources which use the bitmap allocator and involve
mapping ICM memory -- MPTs, CQs, SRQs -- round-robin is not desirable.

What happens in these cases is the following:

ICM memory is allocated and mapped in chunks of 256K.

Since the resource allocation index goes up monotonically, the allocator
will eventually require mapping a new chunk. Now, chunks are also unmapped
when their reference count goes back to zero.  Thus, if a single app is
running and starts/exits frequently we will have the following situation:

When the app starts, a new chunk must be allocated and mapped.

When the app exits, the chunk reference count goes back to zero, and the
chunk is unmapped and freed. Therefore, the app must pay the cost of allocation
and mapping of ICM memory each time it runs (although the price is paid only when
allocating the initial entry in the new chunk).

For apps which allocate MPTs/SRQs/CQs and which operate as described above,
this presented a performance problem.

We therefore roll back the round-robin allocator modification for MPTs, CQs, SRQs.
Reported-by: Matthew Finlay <matt@mellanox.com>
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx4/alloc.c

@@ -71,9 +71,9 @@ u32 mlx4_bitmap_alloc(struct mlx4_bitmap *bitmap)
 	return obj;
 }
 
-void mlx4_bitmap_free(struct mlx4_bitmap *bitmap, u32 obj)
+void mlx4_bitmap_free(struct mlx4_bitmap *bitmap, u32 obj, int use_rr)
 {
-	mlx4_bitmap_free_range(bitmap, obj, 1);
+	mlx4_bitmap_free_range(bitmap, obj, 1, use_rr);
 }
 
 u32 mlx4_bitmap_alloc_range(struct mlx4_bitmap *bitmap, int cnt, int align)
@@ -118,11 +118,17 @@ u32 mlx4_bitmap_avail(struct mlx4_bitmap *bitmap)
 	return bitmap->avail;
 }
 
-void mlx4_bitmap_free_range(struct mlx4_bitmap *bitmap, u32 obj, int cnt)
+void mlx4_bitmap_free_range(struct mlx4_bitmap *bitmap, u32 obj, int cnt,
+			    int use_rr)
 {
 	obj &= bitmap->max + bitmap->reserved_top - 1;
 
 	spin_lock(&bitmap->lock);
+	if (!use_rr) {
+		bitmap->last = min(bitmap->last, obj);
+		bitmap->top = (bitmap->top + bitmap->max + bitmap->reserved_top)
+				& bitmap->mask;
+	}
 	bitmap_clear(bitmap->table, obj, cnt);
 	bitmap->avail += cnt;
 	spin_unlock(&bitmap->lock);

drivers/net/ethernet/mellanox/mlx4/cq.c

@@ -187,7 +187,7 @@ int __mlx4_cq_alloc_icm(struct mlx4_dev *dev, int *cqn)
 	mlx4_table_put(dev, &cq_table->table, *cqn);
 
 err_out:
-	mlx4_bitmap_free(&cq_table->bitmap, *cqn);
+	mlx4_bitmap_free(&cq_table->bitmap, *cqn, MLX4_NO_RR);
 	return err;
 }
 
@@ -217,7 +217,7 @@ void __mlx4_cq_free_icm(struct mlx4_dev *dev, int cqn)
 
 	mlx4_table_put(dev, &cq_table->cmpt_table, cqn);
 	mlx4_table_put(dev, &cq_table->table, cqn);
-	mlx4_bitmap_free(&cq_table->bitmap, cqn);
+	mlx4_bitmap_free(&cq_table->bitmap, cqn, MLX4_NO_RR);
 }
 
 static void mlx4_cq_free_icm(struct mlx4_dev *dev, int cqn)

drivers/net/ethernet/mellanox/mlx4/eq.c

@@ -963,7 +963,7 @@ static int mlx4_create_eq(struct mlx4_dev *dev, int nent,
 	mlx4_mtt_cleanup(dev, &eq->mtt);
 
 err_out_free_eq:
-	mlx4_bitmap_free(&priv->eq_table.bitmap, eq->eqn);
+	mlx4_bitmap_free(&priv->eq_table.bitmap, eq->eqn, MLX4_USE_RR);
 
 err_out_free_pages:
 	for (i = 0; i < npages; ++i)
@@ -1018,7 +1018,7 @@ static void mlx4_free_eq(struct mlx4_dev *dev,
 				    eq->page_list[i].map);
 
 	kfree(eq->page_list);
-	mlx4_bitmap_free(&priv->eq_table.bitmap, eq->eqn);
+	mlx4_bitmap_free(&priv->eq_table.bitmap, eq->eqn, MLX4_USE_RR);
 	mlx4_free_cmd_mailbox(dev, mailbox);
 }
 

drivers/net/ethernet/mellanox/mlx4/main.c

@@ -1654,7 +1654,7 @@ EXPORT_SYMBOL_GPL(mlx4_counter_alloc);
 
 void __mlx4_counter_free(struct mlx4_dev *dev, u32 idx)
 {
-	mlx4_bitmap_free(&mlx4_priv(dev)->counters_bitmap, idx);
+	mlx4_bitmap_free(&mlx4_priv(dev)->counters_bitmap, idx, MLX4_USE_RR);
 	return;
 }
 

drivers/net/ethernet/mellanox/mlx4/mcg.c

@@ -996,7 +996,7 @@ int mlx4_qp_attach_common(struct mlx4_dev *dev, struct mlx4_qp *qp, u8 gid[16],
 				  index, dev->caps.num_mgms);
 		else
 			mlx4_bitmap_free(&priv->mcg_table.bitmap,
-					 index - dev->caps.num_mgms);
+					 index - dev->caps.num_mgms, MLX4_USE_RR);
 	}
 	mutex_unlock(&priv->mcg_table.mutex);
 
@@ -1087,7 +1087,7 @@ int mlx4_qp_detach_common(struct mlx4_dev *dev, struct mlx4_qp *qp, u8 gid[16],
 					  index, amgm_index, dev->caps.num_mgms);
 			else
 				mlx4_bitmap_free(&priv->mcg_table.bitmap,
-						 amgm_index - dev->caps.num_mgms);
+						 amgm_index - dev->caps.num_mgms, MLX4_USE_RR);
 		}
 	} else {
 		/* Remove entry from AMGM */
@@ -1107,7 +1107,7 @@ int mlx4_qp_detach_common(struct mlx4_dev *dev, struct mlx4_qp *qp, u8 gid[16],
 				  prev, index, dev->caps.num_mgms);
 		else
 			mlx4_bitmap_free(&priv->mcg_table.bitmap,
-					 index - dev->caps.num_mgms);
+					 index - dev->caps.num_mgms, MLX4_USE_RR);
 	}
 
 out:

drivers/net/ethernet/mellanox/mlx4/mlx4.h

@@ -783,6 +783,11 @@ enum {
 	MLX4_PCI_DEV_FORCE_SENSE_PORT	= 1 << 1,
 };
 
+enum {
+	MLX4_NO_RR	= 0,
+	MLX4_USE_RR	= 1,
+};
+
 struct mlx4_priv {
 	struct mlx4_dev		dev;
 
@@ -844,9 +849,10 @@ static inline struct mlx4_priv *mlx4_priv(struct mlx4_dev *dev)
 extern struct workqueue_struct *mlx4_wq;
 
 u32 mlx4_bitmap_alloc(struct mlx4_bitmap *bitmap);
-void mlx4_bitmap_free(struct mlx4_bitmap *bitmap, u32 obj);
+void mlx4_bitmap_free(struct mlx4_bitmap *bitmap, u32 obj, int use_rr);
 u32 mlx4_bitmap_alloc_range(struct mlx4_bitmap *bitmap, int cnt, int align);
-void mlx4_bitmap_free_range(struct mlx4_bitmap *bitmap, u32 obj, int cnt);
+void mlx4_bitmap_free_range(struct mlx4_bitmap *bitmap, u32 obj, int cnt,
+			    int use_rr);
 u32 mlx4_bitmap_avail(struct mlx4_bitmap *bitmap);
 int mlx4_bitmap_init(struct mlx4_bitmap *bitmap, u32 num, u32 mask,
 		     u32 reserved_bot, u32 resetrved_top);

drivers/net/ethernet/mellanox/mlx4/mr.c

@@ -346,7 +346,7 @@ void __mlx4_mpt_release(struct mlx4_dev *dev, u32 index)
 {
 	struct mlx4_priv *priv = mlx4_priv(dev);
 
-	mlx4_bitmap_free(&priv->mr_table.mpt_bitmap, index);
+	mlx4_bitmap_free(&priv->mr_table.mpt_bitmap, index, MLX4_NO_RR);
 }
 
 static void mlx4_mpt_release(struct mlx4_dev *dev, u32 index)

drivers/net/ethernet/mellanox/mlx4/pd.c

@@ -59,7 +59,7 @@ EXPORT_SYMBOL_GPL(mlx4_pd_alloc);
 
 void mlx4_pd_free(struct mlx4_dev *dev, u32 pdn)
 {
-	mlx4_bitmap_free(&mlx4_priv(dev)->pd_bitmap, pdn);
+	mlx4_bitmap_free(&mlx4_priv(dev)->pd_bitmap, pdn, MLX4_USE_RR);
 }
 EXPORT_SYMBOL_GPL(mlx4_pd_free);
 
@@ -96,7 +96,7 @@ EXPORT_SYMBOL_GPL(mlx4_xrcd_alloc);
 
 void __mlx4_xrcd_free(struct mlx4_dev *dev, u32 xrcdn)
 {
-	mlx4_bitmap_free(&mlx4_priv(dev)->xrcd_bitmap, xrcdn);
+	mlx4_bitmap_free(&mlx4_priv(dev)->xrcd_bitmap, xrcdn, MLX4_USE_RR);
 }
 
 void mlx4_xrcd_free(struct mlx4_dev *dev, u32 xrcdn)
@@ -164,7 +164,7 @@ EXPORT_SYMBOL_GPL(mlx4_uar_alloc);
 
 void mlx4_uar_free(struct mlx4_dev *dev, struct mlx4_uar *uar)
 {
-	mlx4_bitmap_free(&mlx4_priv(dev)->uar_table.bitmap, uar->index);
+	mlx4_bitmap_free(&mlx4_priv(dev)->uar_table.bitmap, uar->index, MLX4_USE_RR);
 }
 EXPORT_SYMBOL_GPL(mlx4_uar_free);
 

drivers/net/ethernet/mellanox/mlx4/qp.c

@@ -250,7 +250,7 @@ void __mlx4_qp_release_range(struct mlx4_dev *dev, int base_qpn, int cnt)
 
 	if (mlx4_is_qp_reserved(dev, (u32) base_qpn))
 		return;
-	mlx4_bitmap_free_range(&qp_table->bitmap, base_qpn, cnt);
+	mlx4_bitmap_free_range(&qp_table->bitmap, base_qpn, cnt, MLX4_USE_RR);
 }
 
 void mlx4_qp_release_range(struct mlx4_dev *dev, int base_qpn, int cnt)

drivers/net/ethernet/mellanox/mlx4/srq.c

@@ -117,7 +117,7 @@ int __mlx4_srq_alloc_icm(struct mlx4_dev *dev, int *srqn)
 	mlx4_table_put(dev, &srq_table->table, *srqn);
 
 err_out:
-	mlx4_bitmap_free(&srq_table->bitmap, *srqn);
+	mlx4_bitmap_free(&srq_table->bitmap, *srqn, MLX4_NO_RR);
 	return err;
 }
 
@@ -145,7 +145,7 @@ void __mlx4_srq_free_icm(struct mlx4_dev *dev, int srqn)
 
 	mlx4_table_put(dev, &srq_table->cmpt_table, srqn);
 	mlx4_table_put(dev, &srq_table->table, srqn);
-	mlx4_bitmap_free(&srq_table->bitmap, srqn);
+	mlx4_bitmap_free(&srq_table->bitmap, srqn, MLX4_NO_RR);
 }
 
 static void mlx4_srq_free_icm(struct mlx4_dev *dev, int srqn)