net: Add max rate tx queue attribute
This adds a tx_maxrate attribute to the tx queue sysfs entry allowing
for max-rate limiting. Along with DCB-ETS and BQL this provides another
knob to tune queue performance. The limit units are Mbps.
By default it is disabled. To disable the rate limitation after it
has been set for a queue, it should be set to zero.
Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/Documentation/ABI/testing/sysfs-class-net-queues b/Documentation/ABI/testing/sysfs-class-net-queues
index 5e9aeb9..0c0df91 100644
--- a/Documentation/ABI/testing/sysfs-class-net-queues
+++ b/Documentation/ABI/testing/sysfs-class-net-queues
@@ -24,6 +24,14 @@
Indicates the number of transmit timeout events seen by this
network interface transmit queue.
+What: /sys/class/<iface>/queues/tx-<queue>/tx_maxrate
+Date: March 2015
+KernelVersion: 4.1
+Contact: netdev@vger.kernel.org
+Description:
+ A Mbps max-rate set for the queue, a value of zero means disabled,
+ default is disabled.
+
What: /sys/class/<iface>/queues/tx-<queue>/xps_cpus
Date: November 2010
KernelVersion: 2.6.38
diff --git a/Documentation/networking/scaling.txt b/Documentation/networking/scaling.txt
index 99ca40e..cbfac09 100644
--- a/Documentation/networking/scaling.txt
+++ b/Documentation/networking/scaling.txt
@@ -421,6 +421,15 @@
with the CPU that processes transmit completions for that queue
(transmit interrupts).
+Per TX Queue rate limitation:
+=============================
+
+These are rate-limitation mechanisms implemented by HW, where currently
+a max-rate attribute is supported, by setting a Mbps value to
+
+/sys/class/net/<dev>/queues/tx-<n>/tx_maxrate
+
+A value of zero means disabled, and this is the default.
Further Information
===================
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index dd1d069..76c5de4 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -587,6 +587,7 @@
#ifdef CONFIG_BQL
struct dql dql;
#endif
+ unsigned long tx_maxrate;
} ____cacheline_aligned_in_smp;
static inline int netdev_queue_numa_node_read(const struct netdev_queue *q)
@@ -1022,6 +1023,10 @@
* be otherwise expressed by feature flags. The check is called with
* the set of features that the stack has calculated and it returns
* those the driver believes to be appropriate.
+ * int (*ndo_set_tx_maxrate)(struct net_device *dev,
+ * int queue_index, u32 maxrate);
+ * Called when a user wants to set a max-rate limitation of specific
+ * TX queue.
*/
struct net_device_ops {
int (*ndo_init)(struct net_device *dev);
@@ -1178,6 +1183,9 @@
netdev_features_t (*ndo_features_check) (struct sk_buff *skb,
struct net_device *dev,
netdev_features_t features);
+ int (*ndo_set_tx_maxrate)(struct net_device *dev,
+ int queue_index,
+ u32 maxrate);
};
/**
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index cf30620..7e58bd7 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -951,6 +951,60 @@
return sprintf(buf, "%lu", trans_timeout);
}
+#ifdef CONFIG_XPS
+static inline unsigned int get_netdev_queue_index(struct netdev_queue *queue)
+{
+ struct net_device *dev = queue->dev;
+ int i;
+
+ for (i = 0; i < dev->num_tx_queues; i++)
+ if (queue == &dev->_tx[i])
+ break;
+
+ BUG_ON(i >= dev->num_tx_queues);
+
+ return i;
+}
+
+static ssize_t show_tx_maxrate(struct netdev_queue *queue,
+ struct netdev_queue_attribute *attribute,
+ char *buf)
+{
+ return sprintf(buf, "%lu\n", queue->tx_maxrate);
+}
+
+static ssize_t set_tx_maxrate(struct netdev_queue *queue,
+ struct netdev_queue_attribute *attribute,
+ const char *buf, size_t len)
+{
+ struct net_device *dev = queue->dev;
+ int err, index = get_netdev_queue_index(queue);
+ u32 rate = 0;
+
+ err = kstrtou32(buf, 10, &rate);
+ if (err < 0)
+ return err;
+
+ if (!rtnl_trylock())
+ return restart_syscall();
+
+ err = -EOPNOTSUPP;
+ if (dev->netdev_ops->ndo_set_tx_maxrate)
+ err = dev->netdev_ops->ndo_set_tx_maxrate(dev, index, rate);
+
+ rtnl_unlock();
+ if (!err) {
+ queue->tx_maxrate = rate;
+ return len;
+ }
+ return err;
+}
+
+static struct netdev_queue_attribute queue_tx_maxrate =
+ __ATTR(tx_maxrate, S_IRUGO | S_IWUSR,
+ show_tx_maxrate, set_tx_maxrate);
+#endif
+
static struct netdev_queue_attribute queue_trans_timeout =
__ATTR(tx_timeout, S_IRUGO, show_trans_timeout, NULL);
@@ -1065,18 +1119,6 @@
#endif /* CONFIG_BQL */
#ifdef CONFIG_XPS
-static unsigned int get_netdev_queue_index(struct netdev_queue *queue)
-{
- struct net_device *dev = queue->dev;
- unsigned int i;
-
- i = queue - dev->_tx;
- BUG_ON(i >= dev->num_tx_queues);
-
- return i;
-}
-
-
static ssize_t show_xps_map(struct netdev_queue *queue,
struct netdev_queue_attribute *attribute, char *buf)
{
@@ -1153,6 +1195,7 @@
&queue_trans_timeout.attr,
#ifdef CONFIG_XPS
&xps_cpus_attribute.attr,
+ &queue_tx_maxrate.attr,
#endif
NULL
};