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[Xen-devel] [PATCH net-next 4/5] xen: convert to 64 bit stats interface



Convert xen driver to 64 bit statistics interface.
Use stats_sync to ensure that 64 bit update is read atomically
on 32 bit platform. Put hot statistics into per-cpu table.

Signed-off-by: Stephen Hemminger <shemminger@xxxxxxxxxx>

---
v2 - add stats_sync and per-cpu

--- a/drivers/net/xen-netfront.c        2011-06-20 13:34:56.383992463 -0700
+++ b/drivers/net/xen-netfront.c        2011-06-20 13:41:47.207992232 -0700
@@ -70,6 +70,14 @@ struct netfront_cb {
 #define NET_RX_RING_SIZE __CONST_RING_SIZE(xen_netif_rx, PAGE_SIZE)
 #define TX_MAX_TARGET min_t(int, NET_RX_RING_SIZE, 256)
 
+struct netfront_stats {
+       u64                     rx_packets;
+       u64                     tx_packets;
+       u64                     rx_bytes;
+       u64                     tx_bytes;
+       struct u64_stats_sync   syncp;
+};
+
 struct netfront_info {
        struct list_head list;
        struct net_device *netdev;
@@ -122,6 +130,8 @@ struct netfront_info {
        struct mmu_update rx_mmu[NET_RX_RING_SIZE];
 
        /* Statistics */
+       struct netfront_stats __percpu *stats;
+
        unsigned long rx_gso_checksum_fixup;
 };
 
@@ -468,6 +478,7 @@ static int xennet_start_xmit(struct sk_b
 {
        unsigned short id;
        struct netfront_info *np = netdev_priv(dev);
+       struct netfront_stats *stats = this_cpu_ptr(np->stats);
        struct xen_netif_tx_request *tx;
        struct xen_netif_extra_info *extra;
        char *data = skb->data;
@@ -552,8 +563,10 @@ static int xennet_start_xmit(struct sk_b
        if (notify)
                notify_remote_via_irq(np->netdev->irq);
 
-       dev->stats.tx_bytes += skb->len;
-       dev->stats.tx_packets++;
+       u64_stats_update_begin(&stats->syncp);
+       stats->tx_bytes += skb->len;
+       stats->tx_packets++;
+       u64_stats_update_end(&stats->syncp);
 
        /* Note: It is not safe to access skb after xennet_tx_buf_gc()! */
        xennet_tx_buf_gc(dev);
@@ -847,6 +860,8 @@ out:
 static int handle_incoming_queue(struct net_device *dev,
                                 struct sk_buff_head *rxq)
 {
+       struct netfront_info *np = netdev_priv(dev);
+       struct netfront_stats *stats = this_cpu_ptr(np->stats);
        int packets_dropped = 0;
        struct sk_buff *skb;
 
@@ -867,12 +882,13 @@ static int handle_incoming_queue(struct
                if (checksum_setup(dev, skb)) {
                        kfree_skb(skb);
                        packets_dropped++;
-                       dev->stats.rx_errors++;
                        continue;
                }
 
-               dev->stats.rx_packets++;
-               dev->stats.rx_bytes += skb->len;
+               u64_stats_update_begin(&stats->syncp);
+               stats->rx_packets++;
+               stats->rx_bytes += skb->len;
+               u64_stats_update_end(&stats->syncp);
 
                /* Pass it up. */
                netif_receive_skb(skb);
@@ -1034,6 +1050,38 @@ static int xennet_change_mtu(struct net_
        return 0;
 }
 
+static struct rtnl_link_stats64 *xennet_get_stats64(struct net_device *dev,
+                                                   struct rtnl_link_stats64 
*tot)
+{
+       struct netfront_info *np = netdev_priv(dev);
+       int cpu;
+
+       for_each_possible_cpu(cpu) {
+               struct netfront_stats *stats = per_cpu_ptr(np->stats, cpu);
+               u64 rx_packets, rx_bytes, tx_packets, tx_bytes;
+               unsigned int start;
+
+               do {
+                       start = u64_stats_fetch_begin_bh(&stats->syncp);
+
+                       rx_packets = stats->rx_packets;
+                       tx_packets = stats->tx_packets;
+                       rx_bytes = stats->rx_bytes;
+                       tx_bytes = stats->tx_bytes;
+               } while (u64_stats_fetch_retry_bh(&stats->syncp, start));
+
+               tot->rx_packets += rx_packets;
+               tot->tx_packets += tx_packets;
+               tot->rx_bytes   += rx_bytes;
+               tot->tx_bytes   += tx_bytes;
+       }
+
+       tot->rx_errors  = dev->stats.rx_errors;
+       tot->tx_dropped = dev->stats.tx_dropped;
+
+       return tot;
+}
+
 static void xennet_release_tx_bufs(struct netfront_info *np)
 {
        struct sk_buff *skb;
@@ -1182,6 +1230,7 @@ static const struct net_device_ops xenne
        .ndo_stop            = xennet_close,
        .ndo_start_xmit      = xennet_start_xmit,
        .ndo_change_mtu      = xennet_change_mtu,
+       .ndo_get_stats64     = xennet_get_stats64,
        .ndo_set_mac_address = eth_mac_addr,
        .ndo_validate_addr   = eth_validate_addr,
        .ndo_fix_features    = xennet_fix_features,
@@ -1216,6 +1265,11 @@ static struct net_device * __devinit xen
        np->rx_refill_timer.data = (unsigned long)netdev;
        np->rx_refill_timer.function = rx_refill_timeout;
 
+       err = -ENOMEM;
+       np->stats = alloc_percpu(struct netfront_stats);
+       if (np->stats == NULL)
+               goto exit;
+
        /* Initialise tx_skbs as a free chain containing every entry. */
        np->tx_skb_freelist = 0;
        for (i = 0; i < NET_TX_RING_SIZE; i++) {
@@ -1234,7 +1288,7 @@ static struct net_device * __devinit xen
                                          &np->gref_tx_head) < 0) {
                printk(KERN_ALERT "#### netfront can't alloc tx grant refs\n");
                err = -ENOMEM;
-               goto exit;
+               goto exit_free_stats;
        }
        /* A grant for every rx ring slot */
        if (gnttab_alloc_grant_references(RX_MAX_TARGET,
@@ -1270,6 +1324,8 @@ static struct net_device * __devinit xen
 
  exit_free_tx:
        gnttab_free_grant_references(np->gref_tx_head);
+ exit_free_stats:
+       free_percpu(np->stats);
  exit:
        free_netdev(netdev);
        return ERR_PTR(err);
@@ -1869,6 +1925,8 @@ static int __devexit xennet_remove(struc
 
        xennet_sysfs_delif(info->netdev);
 
+       free_percpu(info->stats);
+
        free_netdev(info->netdev);
 
        return 0;
>From shemminger@xxxxxxxxxx Mon Jun 20 13:36:03 2011
Message-Id: <20110620203603.019928129@xxxxxxxxxx>
User-Agent: quilt/0.48-1
Date: Mon, 20 Jun 2011 13:35:11 -0700
From: Stephen Hemminger <shemminger@xxxxxxxxxx>
To: davem@xxxxxxxxxxxxx
Cc: netdev@xxxxxxxxxxxxxxx
Subject: [PATCH net-next 5/5] ifb: convert to 64 bit stats
References: <20110620203506.363818794@xxxxxxxxxx>
Content-Disposition: inline; filename=ifb-stats64.patch

Convert input functional block device to use 64 bit stats.

Signed-off-by: Stephen Hemminger <shemminger@xxxxxxxxxx>

---
v2 - add stats_sync


--- a/drivers/net/ifb.c 2011-06-09 14:39:25.000000000 -0700
+++ b/drivers/net/ifb.c 2011-06-20 13:30:30.135992612 -0700
@@ -41,8 +41,18 @@
 struct ifb_private {
        struct tasklet_struct   ifb_tasklet;
        int     tasklet_pending;
+
        struct sk_buff_head     rq;
+       u64 rx_packets;
+       u64 rx_bytes;
+       unsigned long rx_dropped;
+
        struct sk_buff_head     tq;
+       u64 tx_packets;
+       u64 tx_bytes;
+       unsigned long tx_dropped;
+
+       struct u64_stats_sync   stats_sync;
 };
 
 static int numifbs = 2;
@@ -57,7 +67,6 @@ static void ri_tasklet(unsigned long dev
 
        struct net_device *_dev = (struct net_device *)dev;
        struct ifb_private *dp = netdev_priv(_dev);
-       struct net_device_stats *stats = &_dev->stats;
        struct netdev_queue *txq;
        struct sk_buff *skb;
 
@@ -77,15 +86,18 @@ static void ri_tasklet(unsigned long dev
 
                skb->tc_verd = 0;
                skb->tc_verd = SET_TC_NCLS(skb->tc_verd);
-               stats->tx_packets++;
-               stats->tx_bytes +=skb->len;
+
+               u64_stats_update_begin(&dp->stats_sync);
+               dp->tx_packets++;
+               dp->tx_bytes += skb->len;
+               u64_stats_update_end(&dp->stats_sync);
 
                rcu_read_lock();
                skb->dev = dev_get_by_index_rcu(&init_net, skb->skb_iif);
                if (!skb->dev) {
                        rcu_read_unlock();
                        dev_kfree_skb(skb);
-                       stats->tx_dropped++;
+                       dp->tx_dropped++;
                        if (skb_queue_len(&dp->tq) != 0)
                                goto resched;
                        break;
@@ -120,9 +132,33 @@ resched:
 
 }
 
+static struct rtnl_link_stats64 *ifb_stats64(struct net_device *dev,
+                                            struct rtnl_link_stats64 *stats)
+{
+       struct ifb_private *dp = netdev_priv(dev);
+       unsigned int start;
+
+       do {
+               start = u64_stats_fetch_begin_bh(&dp->stats_sync);
+
+               stats->rx_packets = dp->rx_packets;
+               stats->rx_bytes = dp->rx_bytes;
+               stats->tx_packets = dp->tx_packets;
+               stats->tx_bytes = dp->tx_bytes;
+
+       } while (u64_stats_fetch_retry_bh(&dp->stats_sync, start));
+
+       stats->rx_dropped = dp->rx_dropped;
+       stats->tx_dropped = dp->tx_dropped;
+
+       return stats;
+}
+
+
 static const struct net_device_ops ifb_netdev_ops = {
        .ndo_open       = ifb_open,
        .ndo_stop       = ifb_close,
+       .ndo_get_stats64 = ifb_stats64,
        .ndo_start_xmit = ifb_xmit,
        .ndo_validate_addr = eth_validate_addr,
 };
@@ -153,15 +189,16 @@ static void ifb_setup(struct net_device
 static netdev_tx_t ifb_xmit(struct sk_buff *skb, struct net_device *dev)
 {
        struct ifb_private *dp = netdev_priv(dev);
-       struct net_device_stats *stats = &dev->stats;
        u32 from = G_TC_FROM(skb->tc_verd);
 
-       stats->rx_packets++;
-       stats->rx_bytes+=skb->len;
+       u64_stats_update_begin(&dp->stats_sync);
+       dp->rx_packets++;
+       dp->rx_bytes += skb->len;
+       u64_stats_update_end(&dp->stats_sync);
 
        if (!(from & (AT_INGRESS|AT_EGRESS)) || !skb->skb_iif) {
                dev_kfree_skb(skb);
-               stats->rx_dropped++;
+               dp->rx_dropped++;
                return NETDEV_TX_OK;
        }
 



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