Merge branch 'virtio_rx_merging'

Michael Dalton says:

====================
virtio-net: mergeable rx buffer size auto-tuning

The virtio-net device currently uses aligned MTU-sized mergeable receive
packet buffers. Network throughput for workloads with large average
packet size can be improved by posting larger receive packet buffers.
However, due to SKB truesize effects, posting large (e.g, PAGE_SIZE)
buffers reduces the throughput of workloads that do not benefit from GRO
and have no large inbound packets.

This patchset introduces virtio-net mergeable buffer size auto-tuning,
with buffer sizes ranging from aligned MTU-size to PAGE_SIZE. Packet
buffer size is chosen based on a per-receive queue EWMA of incoming
packet size.

To unify mergeable receive buffer memory allocation and improve
SKB frag coalescing, all mergeable buffer memory allocation is
migrated to per-receive queue page frag allocators.

The per-receive queue mergeable packet buffer size is exported via
sysfs, and the network device sysfs layer has been extended to add
support for device-specific per-receive queue sysfs attribute groups.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 31 insertions, 4 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index d7668b881d08..e985231fe04b 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -668,15 +668,28 @@ extern struct rps_sock_flow_table __rcu *rps_sock_flow_table;
 bool rps_may_expire_flow(struct net_device *dev, u16 rxq_index, u32 flow_id,
                          u16 filter_id);
 #endif
+#endif /* CONFIG_RPS */
 
 /* This structure contains an instance of an RX queue. */
 struct netdev_rx_queue {
+#ifdef CONFIG_RPS
         struct rps_map __rcu            *rps_map;
         struct rps_dev_flow_table __rcu *rps_flow_table;
+#endif
         struct kobject                  kobj;
         struct net_device               *dev;
 } ____cacheline_aligned_in_smp;
-#endif /* CONFIG_RPS */
+
+/*
+ * RX queue sysfs structures and functions.
+ */
+struct rx_queue_attribute {
+        struct attribute attr;
+        ssize_t (*show)(struct netdev_rx_queue *queue,
+            struct rx_queue_attribute *attr, char *buf);
+        ssize_t (*store)(struct netdev_rx_queue *queue,
+            struct rx_queue_attribute *attr, const char *buf, size_t len);
+};
 
 #ifdef CONFIG_XPS
 /*
@@ -1313,7 +1326,7 @@ struct net_device {
                                                    unicast) */
 
 
-#ifdef CONFIG_RPS
+#ifdef CONFIG_SYSFS
         struct netdev_rx_queue  *_rx;
 
         /* Number of RX queues allocated at register_netdev() time */
@@ -1424,6 +1437,8 @@ struct net_device {
         struct device           dev;
         /* space for optional device, statistics, and wireless sysfs groups */
         const struct attribute_group *sysfs_groups[4];
+        /* space for optional per-rx queue attributes */
+        const struct attribute_group *sysfs_rx_queue_group;
 
         /* rtnetlink link ops */
         const struct rtnl_link_ops *rtnl_link_ops;
@@ -2375,7 +2390,7 @@ static inline bool netif_is_multiqueue(const struct net_device *dev)
 
 int netif_set_real_num_tx_queues(struct net_device *dev, unsigned int txq);
 
-#ifdef CONFIG_RPS
+#ifdef CONFIG_SYSFS
 int netif_set_real_num_rx_queues(struct net_device *dev, unsigned int rxq);
 #else
 static inline int netif_set_real_num_rx_queues(struct net_device *dev,
@@ -2394,7 +2409,7 @@ static inline int netif_copy_real_num_queues(struct net_device *to_dev,
                                            from_dev->real_num_tx_queues);
         if (err)
                 return err;
-#ifdef CONFIG_RPS
+#ifdef CONFIG_SYSFS
         return netif_set_real_num_rx_queues(to_dev,
                                             from_dev->real_num_rx_queues);
 #else
@@ -2402,6 +2417,18 @@ static inline int netif_copy_real_num_queues(struct net_device *to_dev,
 #endif
 }
 
+#ifdef CONFIG_SYSFS
+static inline unsigned int get_netdev_rx_queue_index(
+                struct netdev_rx_queue *queue)
+{
+        struct net_device *dev = queue->dev;
+        int index = queue - dev->_rx;
+
+        BUG_ON(index >= dev->num_rx_queues);
+        return index;
+}
+#endif
+
 #define DEFAULT_MAX_NUM_RSS_QUEUES      (8)
 int netif_get_num_default_rss_queues(void);