[PATCH v5 net-next] net: hyperv: Add attributes to show TX indirection table

[PATCH v5 net-next] net: hyperv: Add attributes to show TX indirection table

[Chi Song]

An imbalanced TX indirection table causes netvsc to have low
performance. This table is created and managed during runtime. To help
better diagnose performance issues caused by imbalanced tables, add
device attributes to show the content of TX indirection tables.

Signed-off-by: Chi Song <chisong@microsoft.com>
---
v4: use a separated group to organize tx_indirection better, change 
 location of attributes init/exit to netvsc_drv_init/exit
v5: update variable orders.

 drivers/net/hyperv/netvsc_drv.c | 49 +++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 6267f706e8ee..a1e009edd37e 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -2370,6 +2370,51 @@ static int netvsc_unregister_vf(struct net_device *vf_netdev)
 	return NOTIFY_OK;
 }
 
+static struct device_attribute dev_attr_netvsc_dev_attrs[VRSS_SEND_TAB_SIZE];
+static struct attribute *netvsc_dev_attrs[VRSS_SEND_TAB_SIZE + 1];
+
+const struct attribute_group netvsc_dev_group = {
+	.name = "tx_indirection",
+	.attrs = netvsc_dev_attrs,
+};
+
+static ssize_t tx_indirection_show(struct device *dev,
+				   struct device_attribute *dev_attr, char *buf)
+{
+	int index = dev_attr - dev_attr_netvsc_dev_attrs;
+	struct net_device *ndev = to_net_dev(dev);
+	struct net_device_context *ndc = netdev_priv(ndev);
+
+	return sprintf(buf, "%u\n", ndc->tx_table[index]);
+}
+
+static void netvsc_attrs_init(void)
+{
+	char buffer[4];
+	int i;
+
+	for (i = 0; i < VRSS_SEND_TAB_SIZE; i++) {
+		sprintf(buffer, "%02u", i);
+		dev_attr_netvsc_dev_attrs[i].attr.name =
+			kstrdup(buffer, GFP_KERNEL);
+		dev_attr_netvsc_dev_attrs[i].attr.mode = 0444;
+		sysfs_attr_init(&dev_attr_netvsc_dev_attrs[i].attr);
+
+		dev_attr_netvsc_dev_attrs[i].show = tx_indirection_show;
+		dev_attr_netvsc_dev_attrs[i].store = NULL;
+		netvsc_dev_attrs[i] = &dev_attr_netvsc_dev_attrs[i].attr;
+	}
+	netvsc_dev_attrs[VRSS_SEND_TAB_SIZE] = NULL;
+}
+
+static void netvsc_attrs_exit(void)
+{
+	int i;
+
+	for (i = 0; i < VRSS_SEND_TAB_SIZE; i++)
+		kfree(dev_attr_netvsc_dev_attrs[i].attr.name);
+}
+
 static int netvsc_probe(struct hv_device *dev,
 			const struct hv_vmbus_device_id *dev_id)
 {
@@ -2410,6 +2455,7 @@ static int netvsc_probe(struct hv_device *dev,
 
 	net->netdev_ops = &device_ops;
 	net->ethtool_ops = &ethtool_ops;
+	net->sysfs_groups[0] = &netvsc_dev_group;
 	SET_NETDEV_DEV(net, &dev->device);
 
 	/* We always need headroom for rndis header */
@@ -2665,6 +2711,7 @@ static void __exit netvsc_drv_exit(void)
 {
 	unregister_netdevice_notifier(&netvsc_netdev_notifier);
 	vmbus_driver_unregister(&netvsc_drv);
+	netvsc_attrs_exit();
 }
 
 static int __init netvsc_drv_init(void)
@@ -2678,6 +2725,8 @@ static int __init netvsc_drv_init(void)
 	}
 	netvsc_ring_bytes = ring_size * PAGE_SIZE;
 
+	netvsc_attrs_init();
+
 	ret = vmbus_driver_register(&netvsc_drv);
 	if (ret)
 		return ret;
-- 
2.25.1

Re: [PATCH v5 net-next] net: hyperv: Add attributes to show TX indirection table

[Stephen Hemminger]

On Tue, 21 Jul 2020 03:50:00 +0000
Chi Song <Song.Chi@microsoft.com> wrote:

> +static void netvsc_attrs_init(void)
> +{
> +	char buffer[4];
> +	int i;
> +
> +	for (i = 0; i < VRSS_SEND_TAB_SIZE; i++) {
> +		sprintf(buffer, "%02u", i);
> +		dev_attr_netvsc_dev_attrs[i].attr.name =
> +			kstrdup(buffer, GFP_KERNEL);
> +		dev_attr_netvsc_dev_attrs[i].attr.mode = 0444;
> +		sysfs_attr_init(&dev_attr_netvsc_dev_attrs[i].attr);
> +
> +		dev_attr_netvsc_dev_attrs[i].show = tx_indirection_show;
> +		dev_attr_netvsc_dev_attrs[i].store = NULL;
> +		netvsc_dev_attrs[i] = &dev_attr_netvsc_dev_attrs[i].attr;
> +	}
> +	netvsc_dev_attrs[VRSS_SEND_TAB_SIZE] = NULL;
You know that last line is unnecessary. The variable is static and 
starts out as all zero.

Overall looks good.

Acked-by: Stephen Hemminger <stephen@networkplumber.org>