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

[Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>]

On Tue, 2011-06-21 at 16:35 +0100, Stephen Hemminger wrote:
> 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
> v2.1 - keep rx_errors on checksum error

Thanks. Looks good to me from the Xen side.

Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

> 
> --- a/drivers/net/xen-netfront.c      2011-06-20 14:50:01.271989938 -0700
> +++ b/drivers/net/xen-netfront.c      2011-06-21 08:33:12.851953760 -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;
>  
> @@ -871,8 +886,10 @@ static int handle_incoming_queue(struct
>                       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 +1051,38 @@ 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 +1231,7 @@ 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 +1266,11 @@ 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 +1289,7 @@ 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 +1325,8 @@ 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 +1926,8 @@ static int __devexit xennet_remove(struc
>  
>       xennet_sysfs_delif(info->netdev);
>  
> +     free_percpu(info->stats);
> +
>       free_netdev(info->netdev);
>  
>       return 0;
> 



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel